Fix the extraction of the river names.
Fix the printing when the verbose flag is off.
Add check for adjacent river nodes.

Iterate through each river node and find its two closest neighbours. If
those neighbours are also rivers, then merge the discharges and ditch
one of the rivers (i.e. both rivers are put onto the same node). This
should eliminate the problem of having huge discharges due to the weird
way E-HYPE stores its river mouths (some of them seem along way from
where you'd expect them).

This is probably full of bugs, but I think it's OK.
Fix a number of inconsistencies and make things a bit simpler to read.
Fix the list of permissible field names to pass.
Add support for writing out the HEATING_CALCULATED parameters.

If supplied, write out the HEATING_CALCULATED parameters:
    - downward shortwave
    - downward long wave
    - air temperature
    - air pressure
    - relative humidity
in addition to the other wind forcing parameters (u10, v10).