Add a quick keyword filter

Redmine queries could take a long time. The new keyword filter filters the already retrieved issue list. Filter changes don't issue a new Redmine query so you will get a relatively quick response.

git-svn-id: https://redmine-desktop-client.googlecode.com/svn/trunk@310 86561f23-730a-238f-b720-e77452a7406c
Keyword filter: Also search projects when projects are not pre-filtered.

git-svn-id: https://redmine-desktop-client.googlecode.com/svn/trunk@311 86561f23-730a-238f-b720-e77452a7406c