Fix bugs:

* about and help dialog box are now ko
* erase are now disable when no graphics
* Cursor for FireFox
* Remove label 0km when dbl click measure (for windows)
Fix bugs:

- repair some WCAG issue
- blur the redo and undo after click
- text background set to green
- add missing tooltip
- scroll to opening toolbar
- new color picker
- keep panel open when user press esc to exit from text tool
Merge pull request #53 from jolevesq/fix-issues

Fix issues, comment for the list