Replaced math.h with shogun include.

Pushed changes in other files with similar replacement of math.h.

Squash of previous 2 commits for replacing math.h with shogun include.

Changes in files as suggested in comments - removed unwanted includes lke math.h limits.h and SGIO include.

Squash of all commits including the suggested changes.
Merge pull request #2642 from srgnuclear/trial

Replacing math.h with shogun/mathematics/Math.h.