* POLLOG* macros use the new formatting
removed all old logging functions
* removed old fmt lib from everything except StreamWriter
removed unneeded functions
* fixed review comments
Adds:
- ast/ElementAccess: AST node for x[a] or x[a,b,...] (may be get or set)
- ast/ElementAssignment: AST node for x[a] := b;
- ast/ElementIndexes: AST node to hold all indexes for element lookup
- optimizer/AssignmentOptimizer: optimizes := in different circumstances
