More doc on observable computation
More doc on post-processing scripts
Fix broken links
Document plot scripts
Some doc for file tools
Merge pull request #95 from raoulbq/computing_results

Computing results
Try to improve inner products of linear combinations
Documentation for Gaussian integral
Implement constraints for nesting inner products

The idea of this is to help prevent errors coming
from improper use of inner products.
Adapt Gaussian integral to use compatibility checks
Fix a bug with building matrices by GaussianIntegral class
Adapt SymbolicIntegral to use compatibility checks
Make inhomogeneous inner products for linear combinations more efficient
Reduce code duplication in inner products of LCWP classes