Characteristic decomposition for 1D Euler equations

This PR adds characteristic decomposition for Euler equations in 1D.
The idea of this PR is to add characteristic decomposition for Euler equations in 1D (until now this was not implemented even though the relevant characteristic-wise reconstruction is available in reconstruct.f90). 

Left and right e-vector matrices are computed in ```examples/evec.f90```.
Also total fluctuation within each cell is computed in ```examples/tfluct.90```.
Note that ```evec``` and ```tfluct``` are called by ```/src/pyclaw/sharpclaw/flux1.f90``` and they are problem dependent.

A nose test is added to test this functionality for Woodward-Colella blast wave problem.