* Refactor SymbolTable to improve architecture
* Fix PABCSystem function calls in SPython standard modules
* Fix names search in SymbolTable and CollectNamesFromUsedUnits in Compiler
* Add SemanticRulesConstants.SymbolTableCaseSensitive setting in pcu reader
* Fix case sensitive search in DSSymbolTable class
* Add case sensitive search test cases for SPython
* Leave only one dictionary in SymbolsDictionary class
* Refactor Find function in SymbolsDictionary
* Fix math.pys module
* Fix str.pys
* Imrove Find method in SymbolsDictionary
* DefaultIfEmpty was wrong - need to use Any()
* Replace languageCaseSensitive by languageName data in PCU and caseSensitive parameters in Compiler functions
* Implement SearchDirectories filling in Compiler and move SPython standard modules to their new directory
* Implement search using current language extension first in Compiler
* Delete LibForVB folder and update TestRunner to support different Lib dirs
* Update installer scripts to create separate Lib folder for SPython
* Take into account Lib dirs not found
* Delete supportedSourceFiles variable in Compiler
* Delete unused functions from LanguageIntegrator
