patterns/fas/was: Update FAS, WAS/WA3 pattern files and README.md (#425)

* Add .fas and .was pattern files (Oska DeskMates)

* Update .was pattern file

* Update .was/.wa3 pattern file

* Update README.md

* Update README.md

* Update .fas & .was pattern files

* Update README.md

* Update fas_oskasoftware_old.hexpat

* Added WAS test file

* Update WAS test file

* Update was_oskasoftware.hexpat

* Update was_oskasoftware.hexpat

* Update fas_oskasoftware_old.hexpat

* Update fas_oskasoftware.hexpat

* Update README.md

Replacing backward slashes with forward ones in the `WAS` row.

* Update fas_oskasoftware_old.hexpat

* Update was_oskasoftware.hexpat

README.md

@@ -191,7 +191,7 @@ Everything will immediately show up in ImHex's Content Store and gets bundled wi
 | VHDX | | [`patterns/vhdx.hexpat`](patterns/vhdx.hexpat) | Microsoft Hyper-V Virtual Hard Disk format |
 | VOX | | [`patterns/vox.hexpat`](patterns/vox.hexpat) | MagicaVoxel scene description format |
 | WAV  | `audio/x-wav`  | [`patterns/wav.hexpat`](patterns/wav.hexpat)  | RIFF header, WAVE header, PCM header |
-| WAS | | [`patterns\was_oskasoftware.hexpat`](patterns\was_oskasoftware.hexpat) | Oska Software DeskMates WAS/WA3 (WAVE/MP3 Set) file
+| WAS | | [`patterns/was_oskasoftware.hexpat`](patterns/was_oskasoftware.hexpat) | Oska Software DeskMates WAS/WA3 (WAVE/MP3 Set) file
 | WAD | | [`patterns/wad.hexpat`](patterns/wad.hexpat) | DOOM WAD Archive |
 | WebP | `image/webp` | [`patterns/webp.hexpat`](patterns/webp.hexpat) | Google WebP image |
 | XBEH | `audio/x-xbox-executable` | [`patterns/xbeh.hexpat`](patterns/xbeh.hexpat) | Xbox executable |