Guillotina

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- shell: import 'app_settings'. Fix typo
- doc: Fix example app and other small fixes
[jianaijun]
- feat: Add null and not null operator in int, float and timestamp types in pgcatalog
[rboixaderg]

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- Add is not null operator Search pgcatalog
- Fix order by int and float Search pgcatalog
[rboixaderg]

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- Fix unrestricted Search pgcatalog
- Add filter is null Search pgcatalog
[rboixaderg]

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- Allow to define custom validate url and custom template on email actions
[bloodbare]
- Add in allowed chars in IIDChecker
[rboixaderg]

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- Fixing status code on range request
[bloodbare]

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- Fix potential pg connection leaks
- PG Catalog unrestricted search build count query
- PG Catalog __or, __and operators
[rboixaderg]