Check extension path

It will replace enabled extension with installed one via "make install".
This is primarly to ease up development with jhbuild.
Simplify window geometry hints
Strike-through tasks that are done
Unify license text
Handle task activation signal
Hide the filter button

There seems to be a GTK+ bug concerning used symbolic icon
Show default license notice
Removing unreachable code that generates compilation warning.

(cherry picked from commit 89b23c4cbe881d8949e4815cf09e88111da41a36)
Fix some of compilation warnings

(cherry picked from commit 3e75521c1b8fdc4881d77b86ec9db31c2f9a8c40)

Conflicts:
	lib/preferences-dialog.vala
Update ca.po

Updated translation: added missing strings and improved translation of existing ones.

(cherry picked from commit 1fa0e7a25494ecc0124ebbfa647bbe4be76b311b)
Update ca.po

Some minor corrections to my own translation.

(cherry picked from commit ed765e2592e195fe640a3a8012a50af57d2134db)
Move tasklist view to TaskListPane class
Check extension path

It will replace enabled extension with installed one via "make install".
This is primarly to ease up development with jhbuild.
Simplify window geometry hints
Strike-through tasks that are done
Unify license text
Merge branch 'tasklist'

Conflicts:
	lib/about-dialog.vala
	lib/main-window.vala
Fix segfault upon startup

Thanks to Andrei Dziahel for this patch.

(cherry picked from commit 3e69cd212429426229e9a828a95739bf88f3d2b4)
Make datetime format independent from current locale

Thanks for Andrei Dziahel for the patch

(cherry picked from commit d5f5b698ba592457e3a8e99878c871d559f01a2c)
Dont store date relative to local timezone