new isr function, not working yet. But compiles
isr now working… kinda. must test it more, but seems to be working :)
rings of the input polygon are now closed in the isr method

perhaps the triangulation should do the same? It's more elegant than
what is there now
added ISR function and tolerance now passed as parameter
isr now working: degenerate segments are not inserted anymore
repair2 function removed, repair() now overloaded