Fix: incorrect rearming of Craft weapons

In fact, calculation of craft weapons rearming is bugged.
For example, rearming will be incorrect if:

1. A craft has a cannon.
2. Remaining ammo of the cannon is 101-149 rounds (101 for instance).
3. Remaining ammo on a base is only one clip (x50).

Then the cannon will be fully rearmed, but must have only 151 rounds.
Link to test save: https://dl.dropboxusercontent.com/u/73411168/test.7z