release 0.3.1

- added `25xx` and `26xx` effects in Neo Geo platform for
  envelope period slides
- added `3xxx` and `4xxx` effects in C64 for fine duty/cutoff control
- made home/end keys work
- deleting a single note will delete related instrument value as well
- fix instrument value input when there are less than 16 instruments
- added `Cxxx` effect for mid-song Hz change
- possibly fix a hang when using multiple sound chips
- reduce PC Engine CPU usage

res/Info.plist

@@ -15,17 +15,17 @@
 	<key>CFBundleInfoDictionaryVersion</key>
 	<string>6.0</string>
 	<key>CFBundleLongVersionString</key>
-	<string>0.3</string>
+	<string>0.3.1</string>
 	<key>CFBundleName</key>
 	<string>Furnace</string>
 	<key>CFBundlePackageType</key>
 	<string>APPL</string>
 	<key>CFBundleShortVersionString</key>
-	<string>0.3</string>
+	<string>0.3.1</string>
 	<key>CFBundleSignature</key>
 	<string>????</string>
 	<key>CFBundleVersion</key>
-	<string>0.3</string>
+	<string>0.3.1</string>
 	<key>NSHumanReadableCopyright</key>
 	<string></string>
 	<key>NSHighResolutionCapable</key>