Don't try to track dynamic array dimensions at compile-time
parser: Remove unused variables in cArrayIdx()
parser: Clean up duplicate code in array index parsing
parser: Solve out unnecessary variable in cArrayDecl()
symb: Remove symbDelField() and use symbDelVar() instead
symb: Simplify the way how array dimensions are stored

Previously, VAR/FIELD FBSYMBOLs stored array dimTBs in form of a linked
list of FBVARDIMs. Now it's just a dynamically allocated array of
FBARRAYDIMs, allowing lots of code to become simpler.