Fix file saving.

The app threw a segfault when we saved a file.
This was due to the fact that we didn't deal with the
return variable of write_file method which was freed
causing the segfault. Adding unowned to the bindings
method fix the issue. This closes #8.
Throw file_changed signal when a file is saved.
Implement Ctrl+S save shortcut.
Implement pofiles header management.

I have add to the C library bindings some methods of the header API.
I have add the implementation to get and set the header entry values.
I have add methods to change the last tranlator field when the file
is saved.
Improve opened files panel.

I have add some information to the file
row using the header.
Add custom recent files widget.

This closes #26.
Fix and clean file implementation.

I have moved the part of state modification to the file class
and changed the signals calls.
Only display recent files which exists.
Implement change state action and button.

This closes #37.
Remove editor boxes height calculation.
Improve performance with big files.

I have modified the implementation of message
state. The work is done on the set method now.
In addition number_of_* properties do not call
rebuild every time.
Change Toolbar implementation.

Same header for most implementations changing elements visibility.
Fix typo in Welcome panel.
Modify profile panel.

I have separate the entries in two stacks.
Autocomplete plural form and team email when we select language.

I have added a entry to languages json file that stores what is the
default translators team email.
Merge branch 'master' into gtk3.12

Conflicts:
	src/Makefile.am
	src/messageeditor.vala