---galaga.js---
1. Fixed fire shots burg(single) when merged, happened only when pressing Space key(32), not when clicking left click(right handed).
2. Added fire sound on player, when pressing Space key(32)
---index.html---
1. Erased the duplicate 'bootstrap.min.js' <script> tag.

---To do---
1. To Change the suri gabs between each others ; When merged, it's inevitable lol.
2. To fix merging burg ; even if the player is not captured by an enemy set as 'isSpider', if player shot the enemy, "merging" is occurred.