correcting TeX comments in the SLHA output blocks

Dear Ben,

I think there are some small typos in the comments of various SLHA output blocks.  For example the file `.test/slha2Output` contains the block

 Block msl2 Q= 8.83269909e+02 # super MNS slepton mass^2 matrix - DRbar
   1  1     1.25271482e+05    # (m^_L^2)_{11}
   1  2     0.00000000e+00    # (m^_L^2)_{12}
   1  3     0.00000000e+00    # (m^_L^2)_{13}
   2  1     0.00000000e+00    # (m^_L^2)_{21}

Here the TeX comments are malformed, because they contain `^_`.
This pull request fixes these bugs.

Best,
Alex