Log Message:
(ham/xnec2c) Updated 4.1.5 to 4.2.1

(doc/xnec2c.html)
 4.2: Further to the changes above, I have modified xnec2c so
that more than one FR (frequency range) card can be specified in the
NEC2 file. This makes it possible to calculate frequency-dependent
parameters over separate ranges of interest and thus reduces the time
taken by the program to produce results. Unnecessary calculations
between ranges of interest are also avoided.

Version 4.2.1: Fixed a bug where the DRAW_ENABLED and PLOT_ENABLED
flags where not cleared when the Radiation Pattern Frequency Plots
windows were closed. Made extensive style changes to the source code
so that resources like #defines, #includes and function prototypes
were moved from common.h to the relevant compilation units (.c and .h
files).