More bug fixes and tweaks

Realized a few things that needed fixing:

* The "shine" animation on selected objects and the metal block icon at the bottom were not playing. This is now fixed. There was a pause = false in the wrong line.

* Sped up animations a bit, game feels more fast paced now, as it was intended.

* FIXED A FLICKERING BUG that was driving me nuts. It was a conflict with the particle rendering. Game should look as intended now.

* Fixed major bug where dropping metal blocks and nukes could freeze the game.

* Improved performance on multiple explosions (rendering & sound-wise).

Hopefully it's fun to play without balancing the difficulty!

Enjoy!