Add dummy Crop to SalBitmap implementations

Change-Id: Ib402395f5523a980c9ca098dcd2d8e1ecbbfa7c0
Add dummy Erase to SalBitmap implementations

Change-Id: I5790deb9ab5af6f8678c964af5321264d3bce733
windows opengl: Implement WinOpenGLSalGraphicsImpl::Init() too.

[Blind fix to fix build; real fix to follow after testing.]

Change-Id: Ic4cf2dc74ba4649a2453bc351cdc1d1fad59a0ca
Fix build.

Change-Id: Ibf5d1ccee155cc5807a1a125fde7a7243eab7585
windows opengl: We should actually use Init() from OpenGLSalGraphicsImpl.

Change-Id: I524883b0f0bbce9a8b6f893771f144feeee49934
windows opengl: Transparency of the native widgets.

Change-Id: Ifa6ba5735582effc27ac68556c2367077705d1d6
vcl: Use the current OpenGL context for VirtualDevice and Bitmap if possible

Change-Id: I17f6ce66fb8b5bc027d35b4016ae56c24ee0a738