Move the buttons below the header, just above the table/graph

This emphasizes that they belong to the graph only.
fix small layouting bug

put the buttons in the right place to make the layout consistent
preselect last booked project in project selector
move project chooser into separate widget
cleanup dependencies
reformat dependency list of booking creator

just make it one per line
add dummy projekt chooser to statistics page
modify timecard model to accept optional projects filter

just add a projects parameter to some functions
add projects filter to timecard index controller

make the timecard index controller projects filter aware.
remove static worktime month graph from the statistics template
replace project choose with container in statistics view
make frontend timecard model projects filter aware
make worktimemonthtable and worktimemonthgraph projects filter aware
refactor projectchooser to allow custom option generation

create overridable functions "createOptions" and "postStoreSet" to allow custom
options.
make statisticsView project selector aware
add separation line projectChooser workarounds

we don't want the user to be able to select the separator lines
don't use getModelObject anymore
prevent change event emitting before the projectChooser data has been loaded.
otherwise we have multiple change events that trigger reloads upstream
make the monthgraph/monthtable load depend on the projectchooser change event.

we don't load the monthGraph right away, because it will be reloaded anyway
once the projectChooser starts up and fires it's 'change' event.
By just settings the monthState, the projectChoosers change event will
trigger a graph/table reload once it has finished starting up.
This prevents a double initialization of the monthGraph which was sometimes
visible as a visual 'flickering' of the graph
add missing destroy checks in monthgraph and table