Bump version to 0.6.4 

Merge branch 'v0.6.3' 

Merge branch 'v0.6.2' 

v0.6.1 release date 

Remove the 'In Development' header to reduce confusion 

v0.5.3 release date 

v0.5.2 release date 

Merge branch 'develop'. 0.5.1 release