Merge branch 'swesterfeld-blepsynth-sallen-key-filter', closes #10

* swesterfeld-blepsynth-sallen-key-filter:
  ASE: resampler2: remove, superseded by pandaresampler
  DEVICES: blepsynth/blepsynth.cc: reorder parameter groups
  DEVICES: blepsynth/Makefile.mk: include external/pandaresampler/lib
  EXTERNAL: pandaresampler: add swesterfeld/pandaresampler commit from 2023-02-14 10:18:45
	git submodule add --name pandaresampler https://github.com/swesterfeld/pandaresampler.git external/pandaresampler
	git -C external/pandaresampler checkout 29097dc786b6d75a9deb12e70ec8960a78f7f8f5
  DEVICES: blepsynth: update LadderVCF with drive/reso boost
  DEVICES: blepsynth: optimize filter code if freq/reso/drive are constant
  DEVICES: blepsynth: update LadderVCF, setup cutoff frequency range
  DEVICES: blepsynth: add latency compensation for LadderVCF
  DEVICES: blepsynth: update LadderVCF to version from dsp-research
	- oversample LadderVCF with factor 4, too
  DEVICES: blepsynth: compensate for SKFilter FIR oversampling delay
  DEVICES: blepsynth: reset filter state on filter type change
  DEVICES: blepsynth: reset SKFilter state if filter mode changes
  DEVICES: blepsynth: make cutoff parameter log-scaled
  DEVICES: blepsynth: rename vcf_ to ladder_filter_; minor cleanups
  DEVICES: blepsynth: implement midi velocity handling and add master gain
  DEVICES: blepsynth: smooth drive / reso input for Sallen-Key Filter
  DEVICES: blepsynth: add Sallen-Key Filter

Signed-off-by: Tim Janik <[email protected]>

.gitmodules

@@ -16,3 +16,6 @@
 [submodule "blobs4anklang"]
 	path = external/blobs4anklang
 	url = https://github.com/tim-janik/blobs4anklang.git
+[submodule "pandaresampler"]
+	path = external/pandaresampler
+	url = https://github.com/swesterfeld/pandaresampler.git