* [Core] Fix#15558: Direct expression in ternary operator
* [Core] Added tests for Non-Numeric conditions in ternary op.
* [Core] prevent relational operator chains at grammar level.
* [Core] Rewrite expressions grammar as a layered grammar.
* [Core] Revert to left associative relops (like C/C++) plus tests.
Rename files according 7d233dc ("Gui: Rename generated lexer files
to match core naming pattern"). Note that C space errors (space
before tabs, spaces on blank lines, etc.) still need to be fixed
manually after regenerating lexer file.
