changed True to true

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
added more functions to stdlib

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
added ln builtin function

Signed-off-by: Alexander Skjolden <alex@plastboks.net>
added e, pi and sqrt function

Signed-off-by: Alexander Skjolden <alex@plastboks.net>