check for duplicated stack addresses

Based on https://code.google.com/p/jpcsp/source/detail?r=3569

Fix WWE SmackDown! vs. RAW 2006
Fix save status

Rename u32_le stackAddr to u32
fix bracing
Note the location of a memset variant.
Premultiply for doubled alpha blending if possible.

This makes the effect more accurate where the values were being clamped
before.  Some obscure methods of blending may be slower.
Avoid recalculating replaceBlend so many times.
Avoid premultiplying easy fixed colors.
Dirty the fixed color when premultiplying.
Avoid using fbo copies for the common 2a + 1-2a.

We won't even get it right that often since the copy doesn't deal with
overlap properly.
Improve a possible obscure blend mode.

Seems like this would be likely to get overlap problems.
Optimize fixed color blending that isn't blending.

Gods Eater Burst uses this, for example.
More correctly blend when hitting the frame cap.

If we hit too many blits per frame, fall back correctly in the shader.
Add a hack for Silent Hill games.

Either way has different problems, but it sounds like this will work
better for Silent Hill.  Probably still rendering wrong, unfortunately.
Update Readme.md
typo
Convert all CLUT entries ever loaded.

Some games reuse previously loaded bytes, like World Neverland.  We
displayed bad colors in these cases when we don't convert all the entries.

Technically, this means we're hashing less than used in these cases, but if
we hash more we will get lots of false cache misses.

Fixes #6752.
Merge pull request #6755 from unknownbrackets/clut-fix

Convert all CLUT entries ever loaded
Enable LitPool for ARMv6.
Was originally disabled because vertex JIT wasn't flushing but it now does.
Merge pull request #6756 from xsacha/litpool

Enable LitPool for ARMv6.
Merge pull request #6747 from sum2012/patch-1

Update Readme.md