fix: convert xmap path names for windows

* make sure, unsaved edits only count in editmode (otherwise "watercolour"
  in map configs would already be "edits")

* nicer filenames for backup-xmaps

* catch failed xmap file write access

* unsavededits is now flag (!= 0) and counter - to enable scripts to
  detect "new edits".

new commands:

xmap_delete_backup    deletes the backup xmap

xmap_keep_backup    moves the backup xmap to a regular named spot

xmap_rename    changes the nickname of an xmap
fix: allow creating directories without homedir

With this fix, ac can also create directories relative to the working
directory. This fixes xmaps for users without homedir set.
removed now redundant code

and substituted "copy file and delete original" with "move file"
Two fixes of wrong messages about change to active/spectate mode.
First fix causes, that when player1: plays non-team mode + already is in active mode + changes team to enemy, then will appear message: "you can't change to team $teamname".
Current wrong message is: "you can't change to active mode".

Second fix disables redundant info: "$playername changed to active play", after change to enemy team in non-team modes, when he is already in active mode.