Cream grid jobs fail when no input or output files to transfer. #3415

Fix TransferRequest to behave intelligently when created with an empty
list of transfers. Before, it would issue a transfer command with "NULL"
for source and destination, which fails, causing Cream jobs to go on
hold.
Docs for cream file transfer bug. #3415
Added retries of transient glexec failures. #2415
fix statistics ring buffer so that it no longer aborts after a SetSize operation that reduces the size. #3443.
This should fix the ring buffer problem in mentioned in #3428 also.  parent ticket #2197
===VersionHistory:Pending===
clarified file transfer detail based on condor-users question
initial movement of SMP-policy subsection to 3.5 on startd policy
===GT=== #3447
further rewrite to bring SMP language into the multi-core present
===GT=== #3447
yet more modifications to update terminology and configuraton of slots
===GT=== #3447
HT-ified FAQs about mailing lists and posted link to wiki
edit of 7.8.8 version history item
===GT=== #3395
more updates for describing startd configuration
===GT=== #3447
version history for #3443
===VersionHistory:Complete===
more changes to update docs on multi-core configuration
===GT=== #3447
yet more changes for describing configuration of multi-core machines
===GT=== #3447
mostly formatting edit of 7.8.8 version history item
===GT=== #3404
start of better documentation for partionable slots
===GT=== #3447
Merge branch 'V7_8-branch' into V7_9_3-branch