package selection dialog updated.
don't include package if .pc file is missing.
choose build system in project wizard.
Add library support for Autotools (no for cmake), with a template.
ProjectSettings: add a CheckButton for library project, and a ComboBoxText for build system selection.
WelcomeScreen: add a package selection dialog.
fix CMakeLists.txt for valadoc
Merge pull request #134 from inizan-yannick/master

package selection dialog updated.