Add guesses for jxa and jxi to b2mn parsing

[eldond]

Jeremy Lore wrote in #23:

Here is some logic for default values of jxa, jxi.

First you need to identify the topology. Use nncut and nnreg from b2fgmtry

if (Geo.nncut == 1) && (Geo.nnreg(1) == 4) % SN case
Geo.geometry = 'SN';
elseif (Geo.nncut == 2) && (Geo.nnreg(1) == 8) && (Geo.nnreg(2) == 13) % DDN case
Geo.geometry = 'DDN';
elseif (Geo.nncut == 2) && (Geo.nnreg(1) == 8) && (Geo.nnreg(2) == 12) % CDN case
Geo.geometry = 'CDN';
endif

Then you can guess jxa, jxi. These guesses can be pretty far off depending on the poloidal spacing, but these are the code defaults. Use leftcut and rightcut from b2fgmtry.

if strcmp(Geo.geometry,'SN')
Geo.jxa_guess = ceil(Geo.rightcut(1) - (Geo.rightcut(1) - Geo.leftcut(1))/4);
Geo.jxi_guess = floor(Geo.leftcut(1) + (Geo.rightcut(1) - Geo.leftcut(1))/4);
elseif strcmp(Geo.geometry,'DDN') || strcmp(Geo.geometry,'CDN')
Geo.jxa_guess = ceil((Geo.rightcut(1) + Geo.rightcut(2))/2);
Geo.jxi_guess = floor((Geo.leftcut(1) + Geo.leftcut(2))/2);
end