New Path finding

used Dijkstra with uniform edge weights for path finding. The method is
currently on Buy_Shoot_Mode but could be moved for easier use
Updated projectile and flying units

- Changed tower fire location to be lower.
- Changed projectile physics
- Changed to projectile Update() to use FixedUpdate()
- Added trails for flying units.
Merge pull request #4 from achen052/master

Updated projectile and flying units
New Path finding

used Dijkstra with uniform edge weights for path finding. The method is
currently on Buy_Shoot_Mode but could be moved for easier use
spawning waves
got rid of dijkstra.txt
Click to switch from shoot to buy modes
changes path when turrets and walls are placed

When a turret or wall is placed onto the level, the outside enemies find
a path to the tower using dijkstra. For now if the enemy has already
been spawned it'll stay on its original course, the newly spawned
enemies outside follow the new path. If all paths become blocked the
enemies use the old path for now.
quick changes
Updated Tower Mechanics

- Added tower health
- Added tower fire rate limit
- Added tower resources and score
- Added enemies giving resources and score on death.
Merge branch 'master' of https://github.com/achen052/cs179ProjectVer1

Conflicts:
	Assets/Scripts/Buy_Shoot_Modes.cs
	Assets/Scripts/SpawnWaves.cs
	Assets/_Scenes/TheGame.unity
Merge pull request #5 from achen052/master

Updated Tower Mechanics
pathfinding fix
Merge branch 'master' of https://github.com/mrome007/cs179ProjectVer1

Conflicts:
	Assets/_Scenes/TheGame.unity
scene  changes
GUI

ADDED buttons on bottom. The first two currently do the same thing. They
change modes to place towers. Second one is for walls but dont know
where wall placement is done.

CHANGES to Buy_Shoot_Modes to make shootMode and buyMode public.
Health Bar

Added basic health bar. Will add background/style to it later.
GUI-fixed
added enemy health to flying enemies
added cost to turrets/walls, GUI for resource