Merge branch 'hotfix/0.20.4'
Bumped version to 0.22
aheatmap: enabled choosing type of cell shape
aheatmap: try to fix gap issue in colnames and grobs (issue #19)
Updated vignettes for 0.22 release
Merge branch 'release/0.22'
Merge tag '0.22' into devel

Fixed and enhanced aheatmap