* move `val` definition to avoid undefined
Currently, with only one swath, or not enough points,
val doesnt get defined, so this error gets thrown:
File ".../isce/components/isceobj/TopsProc/runESD.py", line 115, in runESD
if val.size == 0 :
UnboundLocalError: local variable 'val' referenced before assignment
the `np.array` is added so that the `val.size` check makes sense,
as opposed to doing `.size` on a list
* fix string formats in error messages
ISCE_HOME was only used to get the location of the default logging config.
Lots of scripts were using boilerplate to set up this config, so I added
an `isce.logging` helper module which is the same as builtin python logging
but already has the configuration defaults set up for isce.
ISCE_HOME setup is retained in the toplevel `__init__.py`
but can now be removed without affecting functionality.
Scott Staniewicz
Ryan Burns
Eric Gurrola