compiler/libec: (#341, #351, #644, #771) Improved enum type matching and type handling of operator expressions
ecere, ide, eda, samples: Fixed related warnings
- Solved enum types popping up in auto-complete when they shouldn't, e.g. when there are available conversions through base types (#341, #351)
- Fixed issues encountered in samples/games/CornerBlocks (#644)
- An eC enum type minus an eC enum type will give an int rather than en enum
- Validating constant expressions assigned to an enum based on max value, otherwise warning as incompatible (affects bool as well)
- Not applying unit destination type to operands of an operator expression if the unit type is the base unit class (e.g. Angle rather than Radians) (#771)
- Added a conversion property from MinMaxValue to AnchorValue, as it is common to use size values to specify anchors values and it would
  no longer go through the 'int' conversion property