Type loop variables (#758)

* Add cdef to loop variables

* Update CHANGELOG

* EVENTTYPE Overhaul

* Directly use SCIP macros instead of their value

* Update CHANGELOG

* Update CHANGELOG

* Add NODEDELETE to scip.pxi

* Add test prototype for events

* Add more SCIP events

* Add all event types as of SCIP 8

* Add test for event identification

* Update CHANGELOG

* Add method for getting Event names

* Add ability to print stage name as string. Add test.

* Update CHANGELOG

* Add __str__ to Event class

* Update src/pyscipopt/scip.pxi

Co-authored-by: Mohammed Ghannam <mohammad.m.ghannam@gmail.com>

* Add function getconshdlrname

* freeTransform recreates _modelvars

* Removing non-original variables from _modelvars before freeTransform

* Added freeTransform check into test_cuttingstock

* Remove commented code

* Update version

* Rename

* Add check to test_cons

* Change assert to SOS2

* Update INSTALL.md

* Change manylinux

Co-authored-by: Mohammed Ghannam <mohammad.m.ghannam@gmail.com>

* Update CHANGELOG.md

* Update CHANGELOG.md

* Fix outdated time.clock

* Update README

* Add more types

* Update CHANGELOG.md

---------

Co-authored-by: Mohammed Ghannam <mohammad.m.ghannam@gmail.com>
Co-authored-by: Mark Turner <turner@zib.de>
Co-authored-by: Igor Banfi <banfi.igor@windowslive.com>
Co-authored-by: Mark Turner <64978342+Opt-Mucca@users.noreply.github.com>

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Unreleased
 ### Added
+- Added types to loop variables
 - Added methods for getting the names of the current stage and of an event
 ### Fixed
 - Fixed outdated time.clock call in gcp.py