Fix error messages of (un)stick(exempt/invite).

Backported from 1.8
Changed IRCnet's max-bans/max-modes to 64.

Backported from 1.8
Add Tcl8.6 and /usr/lib/x86_64-linux-gnu to Tcl search paths.

Backported from 1.8
Only permanent owners can delete owners.

Backported from 1.8
Fix stripcodes modifying the Tcl object in-place.

Backported from 1.8
Remove length limit of info line.

Backported from 1.8
Fix description for share-unlinks in the config.

Backported from 1.8
Add a config warning to tell users they are in the source directory.

Backported from 1.8
Throw error when writing to read-only variables in server module.

Backported from 1.8