mark engine-version specific fields

[lynxlynxlynx]

and make it obvious. Not everything induced a filetype version change.

[lynxlynxlynx]

From the non-iesdp forum:
ITM v1.0 Flags in NearInfinity
NearInfinity lists bits 12 and 13 in item flags as "EE: Fake Two-handed" and "EE: Forbid Off-hand Weapons",

Bit 13 only works on weapons created through opcode 111. It's used in IWDEE(but also works in 2.0+) to prevent Melf's Meteor's and Spiritual Hammer from allowing off-hand attacks. The Inventory and Record screens still display information for the offhand weapon, and you will retain passive/equipped effects from it, but it is not used to attack.

Bit 12 only alters the animation used in the attack, used by Monk fists, to force them to use the 2-handed attack animation when used alone(empty offhand)