Added FrotaGameMode functions: GetHeroItemByName & RemoveHeroItemByName

[1] table GetHeroItemByName( hscript hero, string itemName, bool stash,
bool dropped )
Use            : function to search an item in hero's invent and return
if present otherwise nil
: For multiple instances of same item, first one is returned
Arguments:
hscript hero   : the player's hero
string itemname: Item name for e.g. "item_blink"
bool stash     : whether to search stash slots also
bool dropped   : whether to search dropped items also

Returns Values :
Returns a table with key,
Item: if found in slots
PhysicalItem: if dropped item
Otherwise nil

[2] bool RemoveHeroItemByName( hscript hero, string itemName, bool
stash, bool dropped )
Use            : function to remove an item in hero's invent if present
: For multiple instances of same item, first one is removed only
Arguments:
hscript hero   : the player's hero
string itemname: Item name for e.g. "item_blink"
bool stash     : whether to search stash slots also
bool dropped   : whether to search dropped items also

Returns Values : true on Success otherwise false
Merge pull request #146 from D-storm/master

Added FrotaGameMode functions: GetHeroItemByName & RemoveHeroItemByName