Added Find Next and Previous buttons
Fixed typos
Remove RTF from the list of supported formats.

Close #202
Fixed case insensitivity
Fixed early feedback
Addressed findNext  feedback
Improved focused event handler
Replaced codemirror onFocus by body focusIn listener
Clean event listener
Make sure suggested name when saving a file has always an extension
Fixed comment
Merge remote-tracking branch 'upstream/master' into addTxtExtension
Forgot semi-colon
Addressed last nits
Merge pull request #203 from beaufortfrancois/addFindFeature

Add basic find previous/next feature
Merge pull request #205 from beaufortfrancois/addTxtExtension

Added txt extension to suggest name when saving it.
Improved search feature.
Removed useless public search methods
Upgraded CodeMirror library rom 3.14.0 to 3.21.0
Changed ocaml to mmlike mode since it has changed in new version of CodeMirror.