Incremental EigCG linear solver addition

Hi Carsten,

   In this forked repository, I have added the files and made changes needed for the Incremental eigCG linear solver. Here is a summary of the changes:
New files:
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solver/ortho.h,  solver/ortho.c, solver/restart_X.h, solver/restart_X.c, solver/eigcg.h, solver/eigcg.c, solver/incr_eigcg.h, solver/incr_eigcg.c, sample-input/sample-incr-eigcg-invert.input
 
Modified files:
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/linalg/blas.h, linalg/lapack.h, solver/solver.h, invert_eo.c, read_input.l, global.h for the input parameters

I have tested the code with and without openMP and it seems to be working fine. The test was done by comparing a certain two point correlation function computed using propagators computed with CG to those computed with eigCG. 

Cheers,
Abdou