Fix performance issue with CaseSensitivity enabled

[aviita]

When CaseSensitive is set to true from JaceOptions, performance should be significantly better than without case sensitivity. Case sensitivity setting was not passed to FunctionRegistry and ConstantRegistry constructors, which caused them to do extra lower case conversions in case variable dictionary was passed to the formula. Fixes issue #75.

New benchmark was created to verify the fix. Benchmark needs to have variables which are provided to CalculationEngine.Calculate(), so VerifyVariableNames() gets called, which causes the extra calls to ToLowerFast().

Below results show ~200 ms improvement when Case Sensitive is true. Results table was created by running benchmark separately with and without fix and copying results to one table.

Engine	Case Sensitive	Formula	Total Iteration	Total Duration (fix)	Total Duration (no fix)
Interpreted	False	something2 - (var1 + var2 * 3)/(2+3)	1000000	00:00:01.6005267	00:00:01.5919016
Interpreted	True	something2 - (var1 + var2 * 3)/(2+3)	1000000	00:00:00.6069845	00:00:00.8390435
Compiled	False	something2 - (var1 + var2 * 3)/(2+3)	1000000	00:00:01.5865326	00:00:01.5770084
Compiled	True	something2 - (var1 + var2 * 3)/(2+3)	1000000	00:00:00.5930012	00:00:00.8189981

Additionally:

• Unit test which tests case sensitivity enabled throws when variable case does not match
• Benchmark uses dictionary copy constructor to avoid throwing due to dictionary being modified with constants and then failing on VerifyVariableNames().

[aviita]

@pieterderycke Any chance of getting this merged?