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 pieterderycke#75][1].

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()`.

[1]: pieterderycke#75