Fixes several errors in the cap gun's text, including every instance of "capss" and a sentence that used "is" instead of "are".
Changes "cap gun" in the firing message to [src], so if the gun is renamed, it will retain that name.
Changes \a to the, since the game never says anything like "you fire A laser gun", etc
consistency
Merge pull request #1549 from Atskadan/grammarfix

Fixes several errors in the cap gun's text