stopULPSound() function is needed

[elshnkhll]

need stopULPSound() function containing I_HALT() macros.

[elshnkhll]

If we add two lines I_END() and I_HALT() after the last macros I_BXI(3) (in the file Mono/Mono.ino for example, line 81 ), calling ulp_run( sizeof(mono) - 4 - 4); should stop the ULP, right?