Textastic for Mac

New:
- tabs: you can now open several files in one window
- window size and position is now saved and used when creating new windows
- added shortcuts for hide status bar and symbols
- the text editor now supports VoiceOver
- added SASS/SCSS syntax highlighting

Fixed:
- File type registration is now less aggressive: on some machines, Textastic replaced the default app for files it shouldn't, like for example HTML files. It was also shown in the "Open With" menu for image files.
- The open panel is now non-modal instead of modal: you could not quit the app or go to other windows while the open panel was shown.
- fixed double click and drag text selection
- fixed file permission issues when the syntax definition is changed from the status bar
- implemented Cmd-Delete and added support for more Emacs shortcuts: Ctrl-K, Ctrl-O, Ctrl-T
- soft tabs: backspace didn't work as expected
- custom code completion files are now loaded from the correct location
- fixed a crash when creating template files
- some other minor bug fixes