calc 2.12.6.3 release

The following are the changes in this release:

Improved gen_v1(h,n) in lucas.cal to use an even faster search method.

Improved are checking in lucas.cal.  In particular both h and n must be
integers >= 1.  In the case of both rodseth_xhn(x, h, n) and gen_v1(h, n)
h must be odd.

Fixed an C code indenting issue that was reported by Thomas Walter
<th dot walter42 at gmx dot de> in zfunc.c.