Release v1.7.3

NEW: add some helper debug methods for probing the stack frames
NEW: add Context.VariableResolver
NEW: map values can now contain expressions
NEW: support for integration with the DelphiMVCFramework (bridge adaptor will be in that repository)
FIX: context missing on two of the TTemplateRegistry.Eval overloads which resulted in some of the config being missing
FIX: general refactorings
FIX: VCL dependency removed. Introductory licensing text is now included in template output when run without the define.
FIX: refactor SempareVersion() helper