PCem

This patch does the following:

• Normalizes directory markers to '/' in readme.txt (to be consistent with the code)
• Updates incorrect rom paths in readme.txt
• Renames some IBM PS/1 and PS/2 machines to better reflect other machine naming
• Puts all devices previously in the rom root directory into subfolders based on the device name, attempting to follow naming conventions as closely as possible

In this, I discovered that several roms are mentioned in the readme but I could not find a reference in the code anywhere. Since I was unsure of their status, I decided to include them here for reference. The list of roms is below:

• europc/50146 [Schneider Euro PC (1988)]
• pc1512/40044.v2 [Amstrad PC1512 (1986)]
• endeavor/1006cb0_.bi0 [Intel Advanced/EV (Endeavor) (1995)]
• revenge/1009af2_.bi0 [Intel Premiere/PCI (Batman's Revenge) (1994)]

One final note: I realize that this is a very sweeping change and none of it is a functional difference, but I personally have a thing for consistency, and some of these small things finally got to me. I do not mean to step on any toes here with regards to previous layout, naming, or formatting.

endeavor/1006cb0_.bi0 and revenge/1009af2_.bi0 are absolutely included in the code, in mem.c, and always have been. I'd suggest double-checking that again; hopefully you didn't remove any references to those, as they are entirely necessary to the basic functionality of the Endeavor and Revenge. pc1512/40044.v2 is likely a typo in the readme that should presumably end with .v1 rather than .v2, and I have no idea about europc/50146 so Sarah will have to weigh in on that one.

If you look at my patch, I didn't remove any of those 4 because I didn't know the status.