Fixed alignment issues
Refactored to add ac_gcm_ghash_low
Changed signature
Moved ac_gcm_ghash_low to backends
Documented asm code
Refactored asm code into macros
Avoid q4-q7 registers in NEON multiplication
Fixed bug in GCM
Added asm ac_gcm_ghash_low in armv7-neon
Small optimizations to ac_gcm_ghash_low in armv7-neon
Removed dead code from armv7-neon, updated documentation