Provides a BitmapDevice: the vcl software renderer

Provides algorithms and data types for bitmap graphics e.g. line and fill
polygon scan conversion, bitmap format iterators, and a SalGraphics-compatible
software renderer

Used for example for wmf / svm files. E.g. used when you do -headless, and
have no DISPLAY set - it's an all-software backend for the LibO graphic
backend. also see [git:vcl/headless].