removed all weapons from starting inventory and made weapons purchasable

[ujjman]

Fixes https://github.com/Terasology/LightAndShadow/issues/248 This PR removes all weapons from starting inventory. It makes weapons purchaseable and attempts to balance them a bit better. We do have different dimensions along which we can assess the (combat) value of a weapon:

• range
• damage
• ammo requirements
• cooldown

Weapon	Range	Ammo?	Damage	Cooldown	Time to Kill	Value
Sword	2	no	20-30	500	2000	50
Waraxe	2	no	40-60	1000	2000	50
Staff (Fireball)	long	infinite	10	300	3000	50
Spear (Melee)	4	no	20-30	1000	4000	50
Spear (Throw)	long	yes (self)	100	100 (slot change)	100	50
Crossbow (Arrows)	long	finite	20	200	1000	30 (1 per arrow)

Time to kill is ceil(playerMaxHealth / damage) * cooldown with playerMaxHealth = 100. Starting money for players is 100.

Melee weapons - sword, axe (, staff, spear)

• Con: need to get close to enemy
• Pro: acceptable to high damage

Ranged, ammo-less weapons - staff (fireball)

• Con: low damage, hard to hit opponent
• Pro: endless ammo, acceptable cooldown, long range

Ranged, ammo-requiring weapons - Crossbow (arrows)

• Con: requires ammo, hard to hit opponent
• Pro: low cool down, acceptable damage, long range

Ranged, pick-up weapons - Spear (throw)

• Con: needs to be picked up, hard to hit opponent
• Pro: very high damage, long range