[CM] Metro command

[Heinrich Taube]

in-tempo scales a unit in beats to a particular tempo value and return  
the value in seconds

(in-tempo .5 60)
-> 0.5

(in-tempo .5 90)
-> 0.33333333333333

the rhythm() function converts a symbolic rhythmic value to a time in  
seconds

(rhythm 'e 60)
-> 0.5

(rhythm 'e 90)
-> 0.33333333333333

(rhythm 'w+s )
-> 4.25


see cm.html