#749 WRAM initialization setting

[rainwarrior]

I created an itialization option for NES internal RAM in r3275 and it seems that it should apply to WRAM for the same reason. Unfortunately there's no standard hub for WRAM, every board maintains its own version of it. A lot of them manually initialize it to 0 (redundant to what FCEU_gmalloc already does). Not sure if there are any that don't use FCEU_gmalloc to allocate their WRAM.

Also might apply to nametable VRAM? (seems to get initialized to 0)

A patch for the first part of the solution is attached. The second part would be to evaluate all the WRAM using mappers and clean out their manual instances of FCEU_dwmemset, memset, etc.

I didn't want to check in the first part (even though it does not change any behaviour with the default setting), until I've had more time to review what all the boards are doing. Created this ticket to remind me to do it later when I have some time and patience for that. (Or someone else can take it up if they're interested.)

[rainwarrior]

Migrated to github where I will eventually finish this:
https://github.com/bbbradsmith/fceux/tree/wram_initialization
https://github.com/bbbradsmith/fceux/issues/4