Added template of special flag "smbx-compatible"

This future flag will enable for current game configuration special
functions:
- warnings about violations of SMBX64 standard
- disallow to use ogg and flac music
- disable non-SMBX options
- forcing apply SMBX64 limits.
Without this flag possible use any features of PGE without limits
Small updates

- External links in new window/tab
- added Raocou's talkhaus link into "Our friends"