Lua bindings for magic

Based on the work made by @bharbich in !2765 (closed).

For now I don't add bindings for active magic effects.

A few usage examples:

    -- print available spells
    local mySpells = types.Actor.spells(self)
    for _, spell in pairs(mySpells) do print(spell.id) end

    -- print available spells (equivalent)
    local mySpells = types.Actor.spells(self)
    for i = 1, #mySpells do print(mySpells[i].id) end

    -- add ALL spells that exist in the world
    local mySpells = types.Actor.spells(self)
    for _, spell in pairs(core.magic.spells) do
        if spell.type == core.magic.SPELL_TYPE.Spell then
            mySpells:add(spell)
        end
    end

    -- add specific spell
    types.Actor.spells(self):add('thunder fist')

    -- check specific spell
    local mySpells = types.Actor.spells(self)
    if mySpells['thunder fist'] then print('I have thunder fist') end