+ This commit also adds overwrites for CommandContexts; this allows for additional remarks for the class.

To many files.

* Fix comments to comply with third-person commenting style
+ Various attributes
+ Various Command-related objects
+ Many more

* Set usage of TokenType.User as an error rather than a warning.

* Remove commented sections and #pragma's

Additionally, changes use of ReadMessages to ViewChannel since that Obsolete was also suppressed by the pragma

* Apply consistency to attributes in the commands extension

This resolves #527.

Not sure if I missed any, putting this up for review.

* Allow preconditions to be used multiple times (for use with groups)

* Fix null channel being passed in RequirePermission preconditions

* c#7 pattern matching

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

* 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.

Also fix an issue where RequireBotPermission may throw if used in a
non-guild channel which required guild permissions.

* Add IChannel.Nsfw, RequireNsfw precondition

* Refactored IChannel.Nsfw to IsNsfw, removed NsfwUtils

Per pull-request feedback

* proper nsfw channel check

Seems I missed this originally, whoops.

The previous name was causing some confusion

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)

This is a breaking change.

Adds a precondition that requires the bot has a specified permission (Resolves #211).

Renames RequirePermission to RequireUserPermission.

This precondition will require that the invoker of the command is the owner of the bot.

This implementation could probably be more efficient, but I
opted for clarity and simplicity where possible.

Add NameAttribute for overriding Name in commands/modules

Command tweaks