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  0.2  fixed  
a  4.0  a  5.0  E2  0.3  master   0.01  10.0
a  4.0  a  5.0  M1  0.4  coupled  E2  a  4.0  a  5.0
</pre>

The general format is

<pre>
initial_band_name   initial_spin   final_band_name   final_spin   multipole_code   value   "fixed"
</pre>

(omitting quotation marks) for a fixed-value matrix element (not to be fitted),

<pre>
initial_band_name   initial_spin   final_band_name   final_spin   multipole_code   value   "master"   lower_limit   upper_limit
</pre>

(omitting quotation marks) for a master matrix element and

<pre>
(same first 6 fields as above) "coupled"   master_multipole  master_initial_band   master_initial_spin   master_final_band   master_final_spin
</pre>

(omitting quotation marks) for a matrix element coupled to a master matrix element.

The fixed/master/coupled status can be changed later in the GUI.

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