Rachel format matrix file

Rachel can import a matrix from a text file.  Currently the Rachel format below is the only one supported, but in the future it will be possible to read the level scheme and matrix from a Gosia input file.

The format of the matrix file is shown below by example.

<pre>
g  0.0  g  2.0  E2  0.7  master   0.01  5.
g  2.0  g  2.0  E2  0.1  master  -5.    5. 
g  2.0  g  4.0  E2  0.5  master   0.01  5.0
g  4.0  g  4.0  E2  0.0  fixed  
</pre>

The general format is

<pre>
initial_band_name   initial_spin   final_band_name   final_spin   multipole_code   value   coupling_code   [lower_limit   upper_limit]
</pre>

The matrix element value is in units of powers of e, b and nuclear magnetons.