As described in GH issue #299, the MAX_GENERATE+1 limit is only
applied when using an address range, not when using CIDR. This
commit changes this to always honor the generator limit.
* refactor target address generation to use the same new function
for both range and CIDR notation
* check the limit for addresses to generate in the new function
* document the generator limit in "fping --help" output
* document the generator limit in the fping man page
* test that the address generation limit applies when using CIDR
notation
* -f with non-existing file
* -f with input file containing comment and empty line
* -g with non-numeric address in "CIDR" format
* -g with one non-numeric address in start resp. end position
* -g with one IPv6 address in start resp. end position
* wrong number or kind of arguments fails and prints usage;
* an empty range silently pings nothing and fping returns 1;
* a too large range fails with an error message;
* a zero CIDR prefix length fails with an error message.
Erik Auerswald
David Schweikert
Martin Topholm
David Schweikert