d-t-w

closes #345410: two_lines_rset, two_cols_rset, two_etypes_rset are badly named replaced by multi_lines_rset, multi_columns_rset, multi_etypes_rset, all taking optional 'nb' argument allowing to specify and exact count. Bw compat is kept, usage of deprecated function updated in cw itself. Also drop custom at_least_two_columns selector (in views.plots) since it was the same as multi_columns_rset. Hopefuly the renaming will help in avoid such pb... We should now decide if we want to deprecate one_* selector in favor of multi_*(nb=1). See note on this at then end of selectors.py

fix #636936: read_permission relation should not be mandatory

fix #615848: undefined 'new' variable was refering to the newly introduced subquery / remove_subquery doesn't take an undefine argument (probable copy/paste from the remove_node call)

some docstring

[doc] reformulate dependencies

[views] FinalView should display an empty string if value is None

merge

move base form renderer label handling into a function to reuse it in CompositeFormRenderer and avoid seeing a tuple in column headers...

minor schema deserialization optimizations

oopb, widget has been renamed

specify formvid=edition to get multiple edition working w/ 3.6