Add support for empty strinngs in SetInputArrayToProcess.

SetInputArrayToProcess ignored empty strings (treating them same as NULL
strings). This behavior makes it impossible to pick arrays that have no
names. Fixing SetInputArrayToProcess to not ignore empty strings. Also
added a check in GetInputArrayToProcess to handle the case where no
array association was specified.

Change-Id: I3c3a9017ea014c2b8f844133956add72c1cf3e6d
Merge topic 'support_empty_arrays' into master

c4c8ce83 Add support for empty strinngs in SetInputArrayToProcess.