Support ICC and older versions of GCC

Previously some versions of gcc (I tested 4.4.6 and 4.4.7) would give the following error:

lib/bench.hh: In function ‘T prime_lower_bound(T)’:
lib/bench.hh:163: error: there are no arguments to ‘sqrt’ that depend on a template parameter, so a declaration of ‘sqrt’ must be available
lib/bench.hh:163: note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated)

Including math.h removes this error and also allows ICC to build the code.
lr_10MB.txt is not included in the data distribution

lr_10MB.txt can be generated locally and is not available in the data distribution.
Automatically generate lr_10MB.txt data

File not provided in data distribution, generate locally.
Merge pull request #1 from teoryn/patch-1

Support ICC and older versions of GCC
Merge pull request #2 from teoryn/master

Fix for missing test data
found by teoryn on github - static const is meaningless
Merge remote-tracking branch 'origin/master' into githubmaster
nits
naming nits.

- real_init -> per_core_init
- init -> global_init
per_core_init -> per_worker_init
Merge branch 'master' of am.csail.mit.edu:/disk/am2/ydmao/metis_release