Added unary relation graphic representation and fix of using env.MODE
Added missing cardinality marker, added setting cardinality into RelationDialog

Added "oneExactlyEnd" marker template. Added setting cardinality (and
modality) at relation dialog.
Fixed layout of cardinality/modality settings at relationDialog
Added supporting of relationship name, changeable by user
Fixed canvas resizing to be recognized by table dragger
Added Postgresql generator, fixed using of right generator

Postgresql generator ingerits from Sql generator. When generating of
sql requested, generator by selected database type is used. Renamed
general generator file.
Added parameter `length` for table columns
Added canvas contextmenu and option for remove table/relation
Fixed reverse engineering, added `start-devel` npm script

Fixed model reengineering by add correct ordering of relations data.
Added updating of child columns when parent column change

Relation columns of child table now reacts on change of parent table
columns.