added 'Starling.registerProgramFromSource()' method
now caching shader programs of FragmentFilters (closes #410)
optimized 'set numVertices' loop in VertexData (closes #406)
raised version to 1.4.1
added changes of version 1.4.1 to change log
updated binary for version 1.4.1
added 'offsetX/Y'-properties to BitmapFont

This allows to manually correct wrong positional data of characters. Bitmap Font tools like GlyphDesigner do not calculate the correct charactor offsets when adding special effects like drop shadows. This leads to wrong horizontal or vertical alignment in Starling. Those new properties allow to make up for this.
Merge branch 'master' into develop