ATV-TW: a trait (and future ancillary) validator for RTW/M2TW

[Squid]

Here's version 0.93.

Just has two minor fixes:
- Fixed the crash that would occur if you had a non-integer value for an Effects line's point value
- Fixed the double minus sign(--) that you'd see for any effect that provided a negative bonus to an attribute.

<<Removed link as this is an outdated version, see this post for the current version>>