Fix reference to null object

to avoid rng.isOnEditable on a null object
Merge pull request #173 from glad2learn/patch-1

Fix reference to null object
Update summernote-fr-FR.js

1) Add button toolbar 'superscript' and 'subscript'
2) Finalize button toolbar 'strikethrough'
Add 'remove image' to ja-JP

#240
updated dutch translations
delete image translated for RU and UA
FIX bug javascript error in XP + IE8.

FIX bug javascript error in XP + IE8.
(styleWithCSS is not compatible ie8)
Merge pull request #248 from takyam-git/patch-1

Add 'remove image' to ja-JP
Merge pull request #250 from n1k1ch/master

delete image translated for RU and UA
Merge pull request #249 from hendrismit/upstream

updated dutch (nl-NL) translations
Merge branch 'patch-5' of github.com:jginfo/summernote into jginfo-patch-5
Merge #251.
Option for disable link target checkbox.
Update summernote-fr-FR.js

Added fr-FR translation for image.remove option.
Merge pull request #260 from loicbenoit/patch-1

Update summernote-fr-FR.js
updated de-DE language to support image remove feature
Merge pull request #263 from tschiela/update-de-lang

updated de-DE language to support image remove feature
Added it-IT translations for recently added features.
new lang Catalan
new lang Catalan