*9037* Show titles in TOC as configured in manager/languages

A very few modifications in core to get more control about how language is shown in TOC in multilang journals.
The aim of the modifications was commented here:
http://pkp.sfu.ca/support/forum/viewtopic.php?f=9&t=13021&p=49967
The new feature also requires modifications submitted to "lib-pkp" submodule.

A deep review of the code (and specially of the literals in locale/en_US/manager.xml) is encouraged.
I don't think this extra consideration of defaults is necessary since you're using the "default:" case statement when determining behavior. It's better if we don't have to maintain code in the future that's specific to an upgrade between older versions; having to mine through history to figure out why code was relevant is painful after it's been forgotten.