by Gilberto"
from pd-l2ork: 50719c4c455291be3ac679486f7e4d72706bd9e4

*patch to add [group] data structure and supporting fixes (work in progress with lingering bug of being unable to display data structure arrays properly, see tiger.pd demo patch in data structures)

- nested plots display properly
- plot is vis'd and unvis'd properly when deleting plot or struct
- commented out ugly plot_displace hack-- multiple plots should work just fine
- separated out garray dependencies into class "old_plot".  This way the changes I made don't affect garrays.  _Very_ ugly hack, but it was pretty simple to implement and will be easy to remove later.
- no crashes when non-existent arrays are entered into a [struct] that has scalars hanging around
- template_cancreate ported from 0.45
- added a function to get the offending struct (to use with "Find last error").  Not using it yet, though.
+ For creating scalars using an object box:
- scalar must have initial "float x float y" fields, in that order.  This means you can't accidentally type the name of the hidden garray structs and create a scalar.  (Nor any other structs that only have a "y" field, etc.)
- broken object box returned if the struct has a bogus array template.  (Although currently I'm just refusing to create such a struct.)

implemented improved version of the g_scalar parsing of owner glist to adopt proper repositioning of scalars.

*gop leaving stale vanila objects
*fixed bug where closing subpatcher of gop patch/abstraction redundantly opens gop patcher/abstraction
*fixed bug where reordering did not properly deselect previously arranged elements

added ability for preset_hub to write/read presets or entire scenes from files. Improved documentation to reflect new additions and to improve existing.

reverted 0.43 backport as its implementation seems unstable when trying to (re)connect to jack via audio properties. Fixed a bug where closing jack while having DAC on would hang pd.