Working if-else blocks

include/dusk/AST/Pattern.h

include/dusk/AST/Stmt.h

include/dusk/IRGen/Context.h

include/dusk/IRGen/IRGenerator.h

lib/IRGen/CMakeLists.txt

lib/IRGen/Context.cpp

lib/IRGen/GenDecl.cpp

lib/IRGen/GenDecl.h

lib/IRGen/GenExpr.cpp

lib/IRGen/GenStmt.cpp

lib/IRGen/GenStmt.h

lib/IRGen/IRGenerator.cpp