compiler: change ShortString->(Some)String and AnsiString->(Some)String overload precedence both for variables and string constants, change unicode constant type from widestring to unicodestring (Delphi compatibility)
new ShortString->(Some)String precedence: ShortString, UTF8String, AnsiString, AnsiString(CodePage) and RawByteString, UnicodeString, WideString and other string types
new AnsiString->(Some)String precedence: RawByteString, UTF8String, AnsiString, AnsiString(CodePage), UnicodeString, WideString, ShortString and other string types

The new logic makes UTF8String more preferrable than other AnsiString types, AnsiString more preferrable than other  AnsiStrings(codepage) and also makes UnicodeString more preferrable than WideString.

git-svn-id: trunk@21057 -