Add dependencies to markdown libraries
More flexibility in Gruntfile

Allows plugins to define additional dependencies, that need to be
loaded before they can be loaded themselves. These will be bundled with
the destination min.js file.

arethusa.comments is doing this with its markdown libraries.
Add a markdown module to arethusa.comments
Parse comments with markdown
Add placeholder hint for markdown input
Merge pull request #418 from latin-language-toolkit/markdown_comments

Markdown comments
Update citation at the right time
Merge pull request #419 from latin-language-toolkit/reference_numbers

Update citations at the right time
Format navigators multi ids in navbar
Merge pull request #422 from latin-language-toolkit/navigator_ranges

Format navigators multi ids in navbar
Always deselect after head changes
Refactor how shouldDeselect is determined

Use a function in globalSettings to ask for this - inside there plugins
are able to define if they want to always deselect or not. The global
alwaysDeselect property takes precedence of course.
Deselect after every depTree action
Merge pull request #423 from latin-language-toolkit/deselections

More flexible deselection handling after actions
Fix a german piece in en i18n
Use a subobject for plugins failed message in i18n
More work on flexible i18n strings
More sentence-like i18n in historyEvent directive
Better i18n for comments
Update plugins service i18n