wrong order of drop constraint/column statements

hi!

with pgadmin built from a fresh svn checkout i have experienced the
following problem, easily reproducible as follows:

i am working on an existing table with some columns and constraints
placed on them. in the table properties window, columns tab i removed a
column and in the constraints tab i removed the constraint placed on
that column. pgadmin produced an incorrect statement order, which was

drop column...
drop constraint...

which resulted in an error saying that the constraint specified does not
exist (as it got removed along with the column). the statement order
should be switched so that the constraint drops are executed before
column drops.

attached is a patch that works for me (pushes the drop constraint
statements before any other statements generated so far) but i do not
know if it will break something else somewhere or if there are such
things as constraints that depend on other constraints and should
therefore be removed in the correct order.

cheers,
M