Blender Git Loki

Implemented general functions to store view context like viewport width/height
and projection matrix, so operators which depends on such things can easily save
settings in operator properties in invoke and then reuse them in exec callback.

This will fix: #24767: Knife tool last operations panel doesn't cause changes even though F6 pop-up does.
#27129: Problem with knife cuts/midpoint type in quad view

Usage is pretty simple:
- From operator template declaration function call ED_view3d_operator_properties_viewmat()
to register all needed properties in operator.
- From invoke callback call ED_view3d_operator_properties_viewmat_set to
store all needed settings in operator properties().
- To access this settings from exec callback, use function
ED_view3d_operator_properties_viewmat_get().

Additional change:
added function apply_project_float() which does the same as
project_float() but accepts actual values for viewport width/height and
projection matrix.