Fixed warning about the ‘text’ property not being always available in ‘msg’
Fixed extractor failing when a specified location attribute is missing from an XML element, now they are optional
Removed/replaced XML entities on translatable strings

Replaced &#10; with \n, which is more readable.
Replaced a &#160; by an actual space; it turns out the non-breaking space had no effect in the current GUI.
Fixed missing sprintf placeholder in public/gui/session/utility_functions.js
Internationalized formatLimitString() in public/gui/session/unit_commands.js
Now the formations tooltip is translated in the GUI (messages were already being extracted)