Spell checker improvements

[alexbrazier]

@RocketChat/core

Closes #195
Closes #263
Closes #281
Closes #289
Closes #306

• Tidy up spell checker implementation
• Fix issues with contractions
• Fix speed issues on windows (pasting bug) - This requires limiting spell checking to one language as switching was causing the speed issues

TODO

• Check that it is working correctly on windows

[alexbrazier]

This pull request will make it so you can only enable 1 language at a time, or disable all together. This change significantly improves the speed of the app, in particular the windows version when typing or pasting in text.

Does anyone have a need to be able to select multiple languages?

[rodrigok]

The limitation of one language per time only exists just to prevent users to select multiple languages or it changes the implementation? Can we keep the multi language and just alert user when select more then 1 language?

Multiple languages is very useful to me.

Thoughts here @RocketChat/core ?

[alexbrazier]

@rodrigok The implementation has changed so that it only allows 1 at a time.

If multiple languages are need then we could disable multiple languages when using Hunspell (I think it is mostly just win 7 and below that uses this). Only issue is that we would have different implementation based on operating systems.

[alexbrazier]

I have now changed it so that if it uses Hunspell then you will only be allowed one language, otherwise it will allow multiple.