Fixed in_network function - returned false results

https://github.com/tehmaze/ipcalc/issues/19
https://github.com/tehmaze/ipcalc/issues/4

The return is now better to read. The rule for detecting if an IP
address is within the network is:
Address <= Testing IP <= Broadcast

This function has only the ability to check an IP address by assuming
the netmask as /32 (IPv4) or /128 (Ipv6). If the tested IP has a
netmask greater than our network it will probably fail.
New function - check_collision(), in_network() deprecated

The new function check_collisions() needs an IP address as argument. It
can be a single address or a complete network. It checks the networks
against each other and returns true if any collisions will be found.
This function is an improvement of the function in_network(). So,
in_network is now marked as deprecated and prints a warning when being
used.