Add input bias parser to core functions.

[anotherjoshsmith]

Need bias parser to automatically detect grid min/max used to generate hills for reweighting directly in python. Much more convenient than asking user to enter sigma and grid min/max manually for each biased CV. New function pulls these values from the bias section of the plumed input file based on user supplied filename and bias method.

[coveralls]

Pull Request Test Coverage Report for Build 29

• 0 of 0 (NaN%) changed or added relevant lines in 0 files are covered.
• 14 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-8.3%) to 89.697%

---

Files with Coverage Reduction	New Missed Lines	%
/home/travis/build/UWPRG/plumitas/plumitas/core.py	14	65.0%

Totals
Change from base Build 28:	-8.3%
Covered Lines:	148
Relevant Lines:	165

---

💛 - Coveralls

[anotherjoshsmith]

Utilitarian git transgression... merging my own PRs for now. This will be strictly forbidden in the future and punishable by cross looks.

Adding modular feature branches to master will help me build up the core functionality more quickly, especially as the organization of the code base takes shape.