* Refine encryption

- Add AES-CTR, blowfish and camellia ciphers

aes-256-ctr
aes-192-ctr
aes-128-ctr
bf-cfb
camellia-128-cfb
camellia-192-cfb
camellia-256-cfb

- Merge the previous PolarSSL and MbedTLS
- Switch to MbedTLS's cipher layer functions
- Add workaround to set cipher operation(encrypt/decrypt)

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

* Add function to get MbedTLS cipher context size

and drop hard-coded ctx sizes

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

ChaCha20 with an extended (96 bit) nonce and a 32-bit counter has
been implemented as crypto_stream_chacha20_ietf() from LibSodium 1.0.4

Please refer to https://tools.ietf.org/html/rfc7539 for details.

Signed-off-by: Syrone Wong <wong.syrone@gmail.com>

Now can use esc key to cancel, and don't change focus after change
server from list

Now can use esc key to cancel, and don't change focus after change
server from list

Add a lock on config form to avoid accidental changes