Merge pull request #513 from Mignari/master

Per-pixel transparency, fix image blit.
Merge pull request #514 from Mignari/master

Fix alpha at color key.
Just use g_configs.unload(config) to unload config files.

Avoids concurrent modification errors.
Merge branch 'master' of https://github.com/edubart/otclient
Fix missing reference for VS project.
Merge remote-tracking branch 'upstream/master'