0.3.1 - QoL Update - Sound Re-design & UI changes

Welcome to my first relevant patch! 

This patch as the name says, is not a content patch, and for now will not add content in the game, but the next major patch is going focused on content! however, the next patch is going to take me a lot of time, principally because I'm the only one working on this game and also I don't do this full-time.

Special thanks to this patch to the people that helped me gathering feedback on this reddit post!: https://www.reddit.com/r/playmygame/comments/1ccq1rc/quest_survivors_a_topdown_classbased_survivor/

UI

• now you can see in the character selection screen the mana cost and cooldown of each ability
• now you can also see the in-game cost of the ability on bottom right in the ability's frame
• changed back arrows in UI: now they have a red color and an 'X' to make it clearer and immediate to new players
• changed frame of the in-game indicators in the bottom right of the screen 

In-game Sprites Update

• new enemy slash (used for boss skeleton knight), now is more noticeable like other enemy projectiles
• new cursor sprite
  

General Audio

• added master volume & added in settings menu
• changed how the game volume varies (now should be more linear)

SFX

• enemy hit: now there are 2 sounds that play randomly
• player hit: uses another sound that makes the hit immediately noticeable
• no more annoying sound caused by multiple sounds stacked on top of each other
• added some new UI SFX to make UI more interactive
• added some various new in-game SFX

Balancing

• mana fruit, tier III only 
  • previously: mana gain up
  • now: max mana up

Bug Fix

• Fixed a bug where buying an upgrade in 'upgrade menu' and then swapping to 'class selection menu' would show visually the previous quantity of gold you had  
• fixed a bug where area damages (like plague mage's ability or corpse detonation) were not showing damage numbers correctly