Bump version to 0.5.4.1

Bump version to 0.5.4

Bump version to 0.5.3

Update RELEASING doc

Merge pull request lightspark#143 from diocles/bug/880391

Check that m_sys->currentVm is not NULL in mouse handlers.

Bump version to 0.5.1

Fix build on natty

Update changelog

Drop alternatives support

Fix build with boost 1.46