enable adding and removing Ndefs and NdefPresets on the fly

[adcxyz]

Currently, NTMI builds all ndefs and NdefPresets on startup.

The option to change the NTMI palette of available NdefPresets/Ndefs would add flexibility:

• removing Ndefs that seem unneeded for the current project
• adding fully configured NdefPresets
• adding conforming Ndefs (amp as first param, complete specs),
  and adding NdefPresets for them

The best approach is probably to restructure the Ndef/Preset loading functions
so they can run for every Ndef independently:
check that Ndef conforms, and if yes,

• make preset for it (with default preset file location)
• add to NTMI repertoire/choice lists