Remove VFP fixme in unw_get_context() with spec citation.

Change-Id: I86a63422e71ac6f23a4e64882a2963f3a28fd7f6
Add more comments and spec citations

Change-Id: If5d2c16fa5468731ad094e8ee232a2fa51b0c28d
Fix up implementation of #7.4.6. Code is slightly hacky, but works.

Change-Id: I2e80a1251468df07e9c78f93d852f51b442ba140
Make a word actually a word for ARM

Change-Id: I56c39d4e4dd2adc10259472b7a028898daac3d50
Remove commented out line

Change-Id: I4549754d7006bbf71ae5e509bc86379a2ce7008a