* Change all Select(... as ...) to OfType

* Add changes according to 194a8aa427

* Add ability to support different types of quotation marks

* Added normal quotation mark to list of aliases, removed single quote mark

* clean up leftover changes from testing

* change quotation mark parsing to use a map of matching pairs

* remove commented out code

* Fix conventions of the command parser utility functions

* change storage type of alias dictionary to be IReadOnlyDictionary

* revert type of CommandServiceConfig QuotationMarkAliasMap to Dictionary

* minor formatting changes to CommandParser

* remove unnecessary whitespace

* Move aliases outside of CommandInfo class

* copy IReadOnlyDictionary to ImmutableDictionary

* minor syntax changes in CommandServiceConfig

* add newline before namespace for consistency

* newline formatting tweak

* simplification of GetMatch method for CommandParser

* add more quote unicode punctuation pairs

* add check for null value when building ImmutableDictionary

* Move default alias map into a separate source file

* Ensure that the collection passed into command service is not null

* Allow setting IgnoreExtraArgs on an individual basis

* Remove passing in the flag as a separate parameter

* VS plz

* Push the RunMode setting out to its own attribute, because fox wants consistency.

Bonus: Removes the need for that godawful 'RunMode.Default'.

* Revert previous commit

* Fox doesn't like module-wide switches 😒

* Addition of FailOnTooManyArgs

* Correct name & only pass in bool

Resovles #870

commit b7fb44a94f
Author: Hsu Still <341464@gmail.com>
Date:   Sat Sep 2 14:34:18 2017 +0800

    Fix more async naming violation

commit e6912e2d02
Author: Hsu Still <341464@gmail.com>
Date:   Sat Sep 2 14:23:04 2017 +0800

    Fix incorrect null xmldocs string

commit da8d23222d
Author: Hsu Still <341464@gmail.com>
Date:   Sat Sep 2 14:17:12 2017 +0800

    Fix CheckPreconditionsAsync

commit 992407407a
Author: Hsu Still <341464@gmail.com>
Date:   Sat Sep 2 14:07:12 2017 +0800

    Add Async suffix to abstract Task methods

* Allow commands to return a Task<RuntimeResult>

This allows bot developers to centralize command result logic by
using result data whether the command as successful or not.

Example usage:
```csharp
var _result = await Commands.ExecuteAsync(context, argPos);
if (_result is RuntimeResult result)
{
    await message.Channel.SendMessageAsync(result.Reason);
}
else if (!_result.IsSuccess)
{
    // Previous error handling
}
```

The RuntimeResult class can be subclassed too, for example:
```csharp
var _result = await Commands.ExecuteAsync(context, argPos);
if (_result is MySubclassedResult result)
{
    var builder = new EmbedBuilder();
    for (var pair in result.Data)
    {
        builder.AddField(pair.Key, pair.Value, true);
    }
    await message.Channel.SendMessageAsync("", embed: builder);
}
else if (_result is RuntimeResult result)
{
    await message.Channel.SendMessageAsync(result.Reason);
}
else if (!_result.IsSuccess)
{
    // Previous error handling
}
```

* Make RuntimeResult's ctor protected

* Make RuntimeResult abstract

It never really made sense to have it instantiable in the first place,
frankly.

* Allow arbitrary attributes to be added to commands

I still don't approve adding type info back into commands, so
I decided to use this solution for allowing arbitrary attributes to be
added to commands.

Add attributes property to ParameterBuilder

Add Attributes properties to info types

* Why on earth git

* Add using for system so that Attribute can be used

* C#7 features in commands, CommandInfo in ModuleBase

* Update TypeReaders with C#7 features and IServiceProvider

* Add best-choice command selection to CommandService

* Normalize type reader scores correctly

* Fix logic error and rebase onto dev

* Change GetMethod for SetMethod in ReflectionUtils

Should be checking against setters, not getters

* Ensure args/params scores do not overwhelm Priority

* Remove possibility of NaNs

It didn't make much sense

* Add grouping of preconditions to allow for flexible precondition logic.

* Fix checking Module Preconditions twice (and none of the command's own)

* Fix command preconditions group 0 looping over every other precondition anyway #whoopsies

* Use custom message when a non-zero Precondition Group fails.

* Fix doc comment rendering.

* Refactor loops into local function

* Considering a new result type

* Switch to IReadOnlyCollection<T> and fix compiler errors

* Revert PreconditionResult -> IResult in return types - Change PreconditionResult to a class that PreconditionGroupResult inherits.

* Feedback on property name.

* Change grouping type int -> string

* Explicitly use an ordinal StringComparer

* Full stops on error messages

* Remove some sillyness.

* Remove unneeded using.

* Improve parameter precondition type safety

Also removes some terrible code which was left over when I first
implemented parameter preconditions. I don't know why that was there.

With this commit, parameter preconditions should be much safer as they
use generic methods instead of janky casting of objects.

* Remove generic CheckPreconditions method

This fixes #304 over foxbot's PR for the same issue.

Currently, commands are case-sensitive. This PR allows for commands to be case insensitive (which is now the default option).

Conflicts:
	src/Discord.Net.Commands/CommandService.cs

For a command to use the DefaultRunMode, it must now have it's RunMode set to RunMode.Default (this is the default value on CommandAttribute now).

This adds an (optional) CommandServiceConfig, as well as a DefaultRunMode for commands.

This resolves #368 (for commands where a RunMode is not explicitly specified, a custom default value should be used)

In theory this should just work, more testing is needed though