Implemented learn_period::get_pending_tasks()
Merge commit '0c35a5b08f171923a1f3793ecf5a689ce460ebfd'

Conflicts:
	libsmo/model/smo.mwb
	libsmo/src/learn_period.cpp
Fixed learn_period::get_pending_tasks()
Added learn_material.ecpp, a minor fix in the database model
Merge commit '624a15370ac42cef9c8993b00369c34e39f4d1a0'

Conflicts:
	libsmo/model/smo.mwb
Added an own "logo" + icon