adds minimal linear test system over Q

fixes release number

Merge pull request #8 from ederc/16-bit-coeffs

adds support for 8 bit and 16 bit coefficients

make a new release for travis support

adds sparse f4 over the rationals

generalized structured input and output, preparing computations over …

…the rationals

non redundant polynomials are no longer considered in the symbolic pr…

…eprocessing step

first version without global variables as preparation for parallel modf4

optimized update process, slightly improved symbolic preprocessing

reintroduces option for generating pbm files of matrices