Building a string with var = var .. "something" has miserable time
complexities. This commit cleans up a lot of that in scripts, focusing
on packing of data with bin.pack and concatenations within loops.
Additionally, a few instances were replaced with string.rep
In most cases (e.g. any of the nmap.socket operations), functions can
take full host and port tables instead of just host.ip and port.number.
This makes for cleaner-looking code and easier extensibility if we
decide to check for a protocol on both TCP and UDP, for instance.
NSE scripts should not send data to stdout with print(). One exception
was not altered: url-snarf states in its documentation that urls are
sent to stdout by default, with a script-arg option to save to a file
instead.
