[cmucl-imp] Snapshot 2014-04

[Raymond Toy]

The April snapshot has been tagged and binaries will be uploaded
soon.

Key changes:

 * This is the last snapshot that will include support for x87. After
   this, cmucl will only run on x86 chips that include support
   sse2. Sse2 was introduced with the Pentium 4 in 2001, 13 years ago.
 * The change in type derivation introduced in the last snapshot has
   been reverted. It's important to have (log -0d0) return
   -infinity+i*pi to get the branch cuts of the special funtions
   correct, using the definitions.  (CMUCL doesn't evaluate the
   functions directly from the definitions.)
 * Add more missing constants for double-double floats.

Ray