[fpc-pascal] JSON and UTF8

[Michael Van Canneyt]

Hi,

Following up on bug 22310
http://bugs.freepascal.org/view.php?id=22310

I enabled the use of UTF8 in the FPC JSON support.

The constructors of the JSON parser/scanner now accept an extra argument 
UseUTF8 which tells them to convert JSON strings to UTF8, not the system codepage.

This should make the jsonscannerUTF8 unit that is floating around redundant.

Michael.