Add the capability to specify a maximum search radius in the source data grid

Add the capability to specify a maximum search radius in the source data grid
for the 'search' interpolation option. A maximum search radius is specified as
an integer value in parentheses added directly after the 'search' keyword, e.g.,

interp_options = ...+search(10)

If no search radius is specified, the search will extend up to a default radius
of 1200 points from the origin of the search.

This new capability is primarily for use with the new lake depth dataset in
WPS v3.6, but may be applied to any other field (including meteorological fields
such as soil moisture) as well.

M    geogrid/src/process_tile_module.F
M    geogrid/src/interp_module.F
M    geogrid/src/proc_point_module.F
M    geogrid/src/queue_module.F
M    metgrid/src/process_domain_module.F

git-svn-id: https://svn-wrf-wps.cgd.ucar.edu/trunk@801 86b71a92-4018-0410-97f8-d555beccfc3a