tools: dot: display data types for columns
tools: dot: display data types for columns

The generated image from the database schema now contains
data types for each column.

Signed-off-by: Jan Viktorin <3eab6ac54c005c4408f608556a6663b7f2abede7@fit.vutbr.cz>

BeeeOn/server,BeeeOn/server,BeeeOn/server,BeeeOn/server