added builtin ceil and floor functions

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
changed print for floats, now ready for decimal point precision

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
stdlib: unzip and filter

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
Merge branch 'master' of github.com:plastboks/byol