Support passing language info to drag and drop setup

- Deriving langInfo moved out of createLayout() and setup initially once-and-for-all and included in layoutInfo to be used e.g. when setting up drag and drop event
- Fixed bug causing en-US lang to be (permanently) overridden by lang set in options. Use jQuery extend deep copy when setting up langInfo to ensure that English text is used if no text is given the the specified lang.
Update Danish language file
Updated dist files
Fixed typo
Minor fixes to satisfy jshint
Limit the size of image uploading
Merge pull request #714 from dandv/develop

Improve English, move changelog to separate file, add features
Merge branch 'feature/drag_drop_lang' of github.com:AgileLeanWorks/summernote into AgileLeanWorks-feature/drag_drop_lang

Conflicts:
	dist/summernote.js
	dist/summernote.min.js
	src/js/Renderer.js
Merge branch 'AgileLeanWorks-feature/drag_drop_lang' into develop
refactor: rename elHolder to holder.
Merge branch 'develop' into limit-filereader-size
rename maximumFileSize to maximumImageFileSize
Update da-DK language

- Moved da-DK video and fontstyle to ext files
- Prepared for #718 (Limit the size of image uploading) language texts
- Minor spell fix
maximumImageFileSize should be null for backward compatibility
Fix wrong option name
Pass message to custom error handler
Merge pull request #718 from HackerWins/limit-filereader-size

Limit filereader size
Merge pull request #719 from AgileLeanWorks/update_da-DK_language

Update da-DK language
add missing  attribute in pt-BR lang file
Merge pull request #734 from matheusrrocha/develop

add missing  attribute in pt-BR lang file