Modernize script coul_hor.sh
Modernize script coul_hor.sh

This commit updates the Coulomb stress calculation script
coul_hor.sh to be consistent with the rest of the Hdef package.

Changes include:
    - Add flags for customizing script actions (specifying target
      fault kinematics with -trg, specifying target fault depth
      with -dep, specifying friction with -fric, specifying
      empirical relation with -emprel)
    - Look for Hdef executables
    - Look for GMT installation
    - Trap remove files generated by script; add -noclean option
      to keep these files (useful for debugging)
    - Improve color palette by making it closer to perceptually
      linear with colortool
    - Improve error exiting with many "|| exit 1"s
    - Add option to calcuate stresses from FSP, FLT files
    - Improve automatic calculation of target fault parameters
      from source fault
    - Update the usage statement

mherman09/Hdef,mherman09/Hdef,mherman09/Hdef