Merge pull request #1 from rkuchumov/gui

Gui
init
Merge pull request #2 from rkuchumov/gui

Gui
Tags::isValid() tests
data, setData tests
filename tests
pro files update
merge with master
Merge branch 'gui'
Merge branch 'master' into tests
name exists test fix
tagsmodel tests
headermodelitem tests
TagsModelItem tests
Merge pull request #4 from rkuchumov/tests

Tests
disabling buttons, cleanup
removed
Merge pull request #5 from rkuchumov/identify

Identify
fetching tags
fetching images