implemented rhythm.generate logic
add 'get <id> size' method (getting all data to know the size is too expensive)
tidy up a bit
figured out a graphic label (does it fit?)
add 0.5 to values coming from aliases in order to mark them as 'aliased'

bad hack, but it seems the most efficient way, since we're not going to use
non-integer numbers
set fgcolor based on 'aliasness'
numbers: treat aliased as lower bound and mark as unaaliased when going up
add 'set <index> <value>' method
now number dragging behaviour works as intended

intended behaviour: aliased values are grey and virtually at position -1, so that you can
only drag upwards from an aliased value. When going upwards, switch to 0 and from then
behave normally. When going down, turn grey after 0 and display aliased value
got correct numarray behaviour working, adapted main patch to it