This patchset adds a preliminary implemenation of geographic (DMS) data axes.
[old!] Feature Request #1078852
gnuplot> help set xdata geographic
`set xdata geographic` indicates that the x coordinate is to be interpreted as
a geographic coordinate measured in degrees. Use `set format x` to establish
how the coordinate appears as an axis tick label. The format specifiers for
geographic data are as follows:
%D = integer degrees
%<width.precision>d = floating point degrees
%M = integer minutes
%<width.precision>m = floating point minutes
%S = integer seconds
%<width.precision>s = floating point seconds
%E = label with E/W instead of +/-
%N = label with N/S instead of +/-
For example, the command `set format x "%Ddeg %5.2mmin %E"` will cause
x coordinate -1.51 to be labeled as `" 1deg 30.60min W"`.
If no special format is provided, the coordinate will be reported as a decimal
number of degrees.
Output should not allow mixing fractional degrees and separate minutes
formatted tabular output not implemented
formatted mouse output not implemented