Shield -1MP should be cumulative and also apply to jumping MP.

[TonicArtos]

Medium and Large Shields have -1MP. This applies to all forms of movement as per questions answered. SSW does not apply -1MP to jumping movement.

Also.

-1MP should be applied for each shield. SSW only applies a single -1 modifier.

To Reproduce

1. Add jumping MP to base chassis.
2. Add two Medium Shields
3. Observe only -1MP to walking MP. (should be -2)
4. Observe no reduction of jumping MP. (currently 0 but fixed in pull for #305)

and

1. Add jumping MP to base chassis.
2. Add two Large Shields
3. Observe only -1MP to walking MP. (should be -2)

Expected behavior

1. Add jumping MP to base chassis.
2. Add two Medium Shields
3. Observe -2MP to walking MP.
4. Observe -2 MP to jumping MP.

and

1. Add jumping MP to base chassis.
2. Add two large Shields
3. Observe -2MP to walking MP.
4. Observe 0 jumping MP.