The format of data we are sending over the network will be flexible when sending...

The format of data we are sending over the network will be flexible when sending over the network in protocol v2. To be able to do this, we create a new va-list function that is creating the buffer to send. Also it makes it easier for the receiver to parse the data; it sends an initial header containing the full length of the buffer to be send. For the individual strings, it sends sub headers containing the length of the upcoming substring to be send. With the header-data-header-data [..] structure we don't need to quote the sub strings finally enabling having all possible character sets in filenames etc..

In the sending function, implement mkdir to actually send it's data
for testing.