More improvements!

1) Fixed yet another group of memory leaks when error is encountered
during parsing
2) Added namespace to Delphi unit names, eg, SysUtils ->
System.SysUtils, TypInfo -> System.TypInfo, etc etc.
3) string optimization for declarations in parameters, eg procedure
X(somevar: string) -> procedure X(const somevar: string)
4) Added ToString to TTokenType so that it can be converted to a string,
during showing of error messages. Instead of "Expected TTEndKeyword, but
found TTLeftBracket", now it reads "Expected 'end' but found '<'