Updated debug node to output other msg properties
Updated debug node test
Added multi-level property functionality
Added tests to check functionality when using multi-level properties
Minor fixes to messages sent from "file in" nodes.

Specifically:

* in the error case, set msg.filename to be the name of the file used (as
  is done in the non-error case),

* in the error case, delete msg.payload so that subsequent nodes only need
  check for a msg.payload to act upon if they don't care about error cases,
  and

* in the non-error case, delete msg.error to avoid passing through errors
  from earlier nodes to a subsequent node that does care about error cases

Messages sent will now always have well-defined behaviour with respect to
the payload, filename, and error in both error and non-error cases.
fix IRC node (once again)
refactoring created incorrect object references - which weren't picked up.
(sorry) -  Addresses Issue 439
Merge pull request #437 from hindessm/file-query-node-usability

Minor fixes to messages sent from "file in" nodes.
Don't let IRC node try to join channels multiple times...
Addresses #447
Allow Raspberry Pi node to set initial output level.
Fix for #443
Also allow (optional) initial read of input pins on deploy.
Moved to Category Raspberry Pi 
(other Pi related nodes will be updated to match soon).
Merge pull request #433 from anna2130/change-node-multi-level-properties

Change node: Multi-level properties
Tidy up node label and edit dialog
Merge pull request #422 from anna2130/debug

Updated debug node to output other msg properties
input labels
Fix merge error
Subflow stuff

This commit will get squashed before merging to master
Make subflows draggable and editable
Add subflow history support
Add create subflow menu option
Update palette labels for overly long labels
Update menu options when tab/flow renamed