GS2 pitch angle and energy grid

The energy grid has been improved (7/29/02) to use the Candy/Waltz scheme.

Detailed documentation to follow. Use the ingen code (in distribution) for guidance in the meantime. I recommend using
    negrid = 16
    ecut = 6.0
as defaults. The pitch angle grid remains as described in article noted below.

A concise description of the GS2 pitch angle and energy grid choices may be found in the article entitled "Comparison of Initial Value and Eigenvalue Codes for Kinetic Toroidal Plasma Instabilities" by M. Kotschenreuther, et al., in Computer Physics Communications, Vol. 88, page 128, 1995.

Allowed values of ngauss:

1, 2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24, 32, 40, 48

The old logic for setting negrid, nesub and nesuper went like this:

Default values (if nothing at all is chosen) are:
    nesub = 8
    nesuper = 2

which implies negrid = =10

The preferred way to choose something else is
    nesub = whatever
    nesuper = whatever

and then negrid will be set appropriately.

The backwards compatible way to set energy grid is:
    negrid = whatever

where nesuper = 2 and nesub is set appropriately.

Other possibilities are:
    negrid = whatever
    nesuper = whatever

and then nesub is set to negrid - nesuper.

If all three are set by the user, and if the value of nesub supplied by the user does not equal (negrid - nesuper), then nesub is set to equal (negrid - nesuper), and the discrepancy is reported to the runname.error file.

Allowed values of nesuper:

2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15

Allowed values of nesub:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 20, 24, 32, 48, 64