Load SoundGroup table from entity XMLs

[Matei]

It should be possible to specify a sound for each animation, using code such as:

<Entity>
        ...

	<SoundGroups>
		<Walk>infantry_walk.xml</Walk>
		<Run>infantry_run.xml</Run>
		<Death>screams.xml</Death>
		<Gather_wood>axe_chopping.xml</Gather_wood>
		<Gather_stone>pickaxe.xml</Gather_stone>
	</SoundGroups>
</Entity>

These should be in a hashmap in CEntityTemplate.

[(none)]

Milestone Playability Demo deleted