is so they are safer to use in threaded programs.

I also changed it's interface slightly.  In particular, I removed the min_diff
parameter and replaced it with an explicit min_size parameter.

parallel_for routines.

verbose time remaining estimation.

murmur_hash3() to avoid violation of the strict aliasing rule.  In particular,
the previous version didn't work correctly in gcc 4.7.2 when optimizations were
enabled.

the mean average precision when matching SURF descriptors
by about 2%.

region and therefore finds more interest points.

in addition to just raw ranking accuracy.  This changes their return types
from double to matrix<double,1,2>.

so that we avoid a common cmake warning.

ASCII matrices using the format used by operator<<.