Bugfix with removing layout items
Added method to add layout items in order prevent the API user of reconfiguring layout items after they have been removed
In order to prevent sublayout items subviews to be removed while removing the sublayout the called method has been changed and a test has being introduced to ensure this behavior.
Renamed method in order to improve clearance and made a distinction between inner API and public one
Added method to remove layout items in order to prevent the API user from finding an index if he has the item instance already
Major change

Margin now becomes padding
Added tests and enabled code coverage generation by default
Merge branch 'develop' of https://github.com/mkloeppner/MKLayoutLibrary into develop
Let the layout item set its frame
Let the layout item set its frame
Added base implementation of flow layout
Clean up initializer
Support different orientations for flow layout
Add support for size
Fixed bug when the line break occours. The available space should never exceed
Add support for padding
Created a test case for precalculating row/column heights
Enabled gravity
Renamed method
Pixel perfect linebreaks