Adds classes for optics:
- AttachmentOpticsRIS 
- AttachmentCarryHandleMount

For attachements
- AttachmentShortRIS
- AttachmentRISUnderBarrel

For muzzles
- AttachmentMuzzle9_18
- AttachmentMuzzle9_19
- AttachmentMuzzle45
- AttachmentMuzzle556
- AttachmentMuzzle545
- AttachmentMuzzle308

Both weapon mods and attachments mods can use those make optics and other parts shareable between weapons.

- ver 0.0.1 - initial version
- ver 0.0.2 - fix AttachmentTypes visibility in properties
- ver 0.0.3 - added carry handle and muzzle attachment types
- ver 0.0.4 - added more muzzle attachments and underbarrel RIS rail
- ver 0.0.5 - compatibility with 0.9.8

AttachmentsCompatibility

Now compatible with 0.9.8 version of the game.
Will be deprecated as soon as all the mods switch to using vanilla classes.

Does NOT contain playable content. 
Allows weapons to share attachments.