Add a region component

This patch adds a pixman_region like component in the utility components
of FreeRdp.
The data structure is exactly the same as in pixman_region but the implementation
differs as we need fewer methods.
The patch contains the corresponding unitary tests.
Fix remoteFx encoder with topleft and bottomright rectangle

This patch fixes the case where with a topleft and a bottomright
rectangle, the encoder would send the full screen instead of only the
intersected tiles.
Some fixes after Norbert code review

There were a bug when the rectangles extents where not at the origin.
Some debugging statement have laso been removed.
Fixes before pullreq

Replaced zmalloc by calloc.
Moved region from utils to codec.
Fixed some typo and corner cases.
Fixes in intersection + checks

Fix a bug in the extents of an intersection.
Add some checks and assert that helps when using the remoteFx encoder.
A speedup for intersection when bands are above the target rect.
Merge branch 'remoteFx_fix2' of https://github.com/hardening/FreeRDP into hardening-remoteFx_fix2

Conflicts:
	libfreerdp/codec/test/CMakeLists.txt