Bump version to 0.5.0 and API version to 0.6.
Bump version to 0.5.0 and API version to 0.6.

gjtorikian/lasem,gjtorikian/lasem,janmarthedal/mathml2svg,gjtorikian/lasem,janmarthedal/mathml2svg,gjtorikian/lasem,wavewave/lasem,janmarthedal/mathml2svg,wavewave/lasem,wavewave/lasem,janmarthedal/mathml2svg,wavewave/lasem