move to support only one branch

This patch allows us to stick to only one branch - 2.11.0-picodata instead of two (three?). Previously there were 2.11.0-picodata and picodata-submodule. Going forward all changes should go only to 2.11.0-picodata (switching to next release when needed)

This patch is a merge of locally rebased version of changes-required-only-by-picodata-product merged into 2.11.0-picodata

Close #34 (closed) (see more context in this issue)

Next step after this is merged would be to move submodule pointer in picodata repo to the head of 2.11.0-picodata (see picodata/picodata/picodata!709)