Fix enter behaviour in editables that cannot contain paragraphs

If the active editable does not allow paragraphs as its content (according
to http://www.w3.org/TR/2010/WD-html-markup-20101019/p.html, the element
must allow flow content), a linebreak is inserted instead of a paragraph
when pressing the Enter key, as if using shift-Enter.
Merge pull request #920 from maschonber/hotfix-linebreak-paragraph

Fix enter behaviour in editables that cannot contain paragraphs
Prepare aloha release.
[maven-release-plugin] prepare release alohaeditor-0.23.9-commercial
[maven-release-plugin] prepare for next development iteration
[maven-release-plugin] prepare release alohaeditor-0.23.9
[maven-release-plugin] prepare for next development iteration
Fix issue with empty tabs contents on toolbar

The algorithm must be enhanced, search for buttons
except with class aloha-multisplit-toggle, more info
on the code
Merge pull request #926 from danyg/Branch_commercial-hotfix-empty-cells

Fix issue with empty tabs contents on toolbar
Remove trailing whitespaces in code introduced from pull request
Merge remote-tracking branch 'daniel/commercial-hotfix-batu-fr1' into commercial-hotfix-batu-fr1

Conflicts:
	build/hotfix-changelog.md