Add database diagrams#1962

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MKleusberg wants to merge 13 commits intomasterfrom

0xd800-diagrams

Commits on Aug 10, 2019

Commits on Aug 12, 2019

Commits on Aug 15, 2019

Reduce diagram tables width
mgrojo
committed

Commits on Sep 7, 2019

Shorten tab name and add it to the initial tab list in main window
mgrojo
committed

Commits on Sep 8, 2019

Add lines representing relations to diagram
mgrojo
committed