## Link to GitHub Issue or related Pull Request, if one exists
#653
## Description of change
By default, BAT Positive / Negative binds trigger when the stick is
tilted 10% off the center.
This needs a bit more customization since:
1. User may want to customize the center point (e.g., guitar controller
neutral position)
2. User may want to adjust the sensitivity (e.g., guitar controller tilt
angle to trigger wailing).
## Testing
WIP
## Link to GitHub Issue, if one exists
n/a
## Description of change
For buttons and lights, it's possible to have multiple alternatives.
When you create alternatives and then clear then, the config files
continue to have stale entries. This is because alternatives are stored
in a vector and elements are never deleted when unbound; they get
written out to the XML on modification.
These stale XML entries live forever, and get loaded on next startup of
spice.
This PR fixes that by deleting stale entries - basically, XML nodes will
be kept only until the last valid node (properly bound button or light),
trimming the trailing invalid entries.
## Testing
Manual testing, validating XML.
bicarus