Reduced charger's max charge, make it fire when it reaches max.

The original charge cannon is so overpowered it's ridiculous. The
strongest weapon in the game, unlimited ammo, and the only setback
it has is that you need to charge it a bit. The lack of balance
obsoletes the laser weapon, which is fine, but it also obsoletes
homing missile weapons, *including* ones that are newer and more
expensive than the charge cannon!

Now, it's much more balanced. You actually need to shoot the thing
before it hits max (or have your target in sight when it does),
rather than being able to just hold the button at max forever and
release when optimal like you previously could. Basically, the charge
cannon is still the weapon which does the most damage, but it's now
much harder to use. Incidentally, not only should homing missiles
be a sensible option now, even the laser cannon has a place after
the charge cannon becomes available.

src/player.cpp

@@ -18,6 +18,7 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include "Starfighter.h"
 
 object player;
+bool charger_fired = false;
 
 /*
 Initialises the player for a new game.
@@ -118,13 +119,23 @@ void doPlayer()
 			{
 				if (engine.keyState[KEY_ALTFIRE] && !(engine.keyState[KEY_FIRE]))
 				{
-					limitCharAdd(&player.ammo[1], 1, 0, 200);
+					if (!charger_fired)
+					{
+						player.ammo[1] += 1;
+						if (player.ammo[1] >= 125)
+						{
+							fireBullet(&player, 1);
+							player.ammo[1] = 0;
+							charger_fired = true;
+						}
+					}
 				}
 				else
 				{
 					if (player.ammo[1] > 0)
 						fireBullet(&player, 1);
 					player.ammo[1] = 0;
+					charger_fired = false;
 				}
 			}