recon2d errors for 0 elements

[millerta]

recon2d does not exit gracefully for 0 elements and creates strange epsilon values

 33         epsilon REAL     scalar          scalar const perma   l  1.000E-15
 34        epsilonl REAL     scalar          scalar const perma   l  7.692+137
 35        epsilona REAL     scalar          scalar const perma   l  2.665+288
 36        epsilonv REAL     scalar          scalar const perma   l   Infinity

[millerta]

Added check and early exit for 0 elements, epsilon values are still being set to bad values.
Need to figure out where that is happening and fix it.

[millerta]

recon is used to call the recon2d and other routines. It also uses setsize to assign epsilon values.
For a 0 element mesh the eps values are junk. Added check for 0 elements and exit.
This avoids bad values assigned to the epsilons.
Note there will be a general error msg from control_command_lg due to ierror = -1
Now the output for 0 elements will look like:

recon/0

WARNING Recon Early Exit: 0 elements

RECON: done.
error in command : recon/0