Fixes #50: NextMethod() not handling arguments properly
Fixes #52: Supports ..n notation for varargs
Fixes Issue #53: $ and $< should not be generic
Fixes bug when removing element from pair lists
Added IDEA files to .gitignore
Adds support for factors to match()

These seems to be special cased: if you call match()
with one factor argument and the other string, the
factor is converted to strings. This doesn't seem
to happen with other classes that declare an
as.character method.