quoting of tablenames and field names

fix for wrong sequence name quoting

fix for wrong sequence name quoting 2

reverted test to quoted rname

rname passed asis. freedom in table names and field names. Case sensitivity in field and table names

removed test of allowed char sequence in table and field names, there is no limit anymore

fixed some troubles with postgresql drop(). Better Row.__getitem__(): should not be much slower.  Added a ignore_field_case parameter to allow Field('F')!=Field('f') on databases supporting case sesitivity.

different mysql drivers handled in quoting test.

improved handling of foreing keys

fix with quoted names in SQLTABLE.  fix for ORDER BY

handle references on non "id" fields

check reference expression against table list first
fixed typo, thanks Dean
Merge pull request #317 from michele-comitini/entity_quoting

quoting of tablenames and field names
optional label in checkbox widget, fixed issue 1797, thanks Richard