Reordered breadcrumb items.
Rather use language.name.
Moved strCmp to PTL.utils.
Moved zoom-related code into its own namespace.
Properly namespace common code.

This will still need more love to separate the init into manageable
functions.
Allow quick-switch of languages while retaining context.

This is specially useful for project administrators and will save lots
of clicks or manual URL editions.

For now all the languages available for the current project are listed,
although we could limit the list to the language selection made by the
user in the personal settings.

Fixes bug 1489.