Step-based volume adjustment

Apologies! Here are the individual libraries.

WAV Trigger
Metro
AltSoftSerial

I deleted them and reinstalled them, but I seem to be getting more error messages:

Arduino: 1.8.5 (Windows Store 1.8.10.0) (Windows 10), Board: "Arduino/Genuino Uno"

C:\Users\sixsmith\Documents\Arduino\libraries\Metro\Metro.cpp:42:16: warning: extra tokens at end of #ifdef directive

#ifdef NOCATCH-UP

^

c:\program files\windowsapps\arduinollc.arduinoide_1.8.10.0_x86__mdqgnx93n4wtt\hardware\tools\avr\bin../lib/gcc/avr/4.9.2/../../../../avr/bin/ar.exe: unable to rename 'core\core.a'; reason: File exists

exit status 1
Error compiling for board Arduino/Genuino Uno.

I should probably point out that I could get the WAV Trigger's example file to work fine previously, although now it doesn't seem to be running either (same error message appears).