Linux layer 7 packet classifier

1. when doing a release, update the version in configure.ac and regenerate configure as this affects the output of l7-filter --help

2.
few compile warning that i've ignored for the time being. The first one will probably cause gcc faults in the new releases (tested with 4.2.3)

l7-classify.cpp: In function 'char** readl7dir(std::string)':
l7-classify.cpp:160: warning: deprecated conversion from string constant to 'char*'


l7-filter.cpp: In function 'void handle_cmdline(int&, std::string&, int, char**)':
l7-filter.cpp:174: warning: comparison is always false due to limited range of data type
l7-filter.cpp:174: warning: comparison is always false due to limited range of data type
l7-filter.cpp:181: warning: comparison is always false due to limited range of data type
l7-filter.cpp:181: warning: comparison is always false due to limited range of data type
l7-filter.cpp:193: warning: comparison is always false due to limited range of data type
l7-filter.cpp:193: warning: comparison is always false due to limited range of data type

3. Path changes should be done with ./configure as this can propergate to other aspects of the compile.
I think by default it looks in /usr/local/lib and /usr/lib however I don't think changing PREFIX here changes where to look for libs. Adding -L{path} to LDFLAGS is the proper way to where to look for libs.

As configure.ac uses PKG_CHECK_MODULES([NFNETLINK], [libnetfilter_conntrack libnetfilter_queue]) and hence the ${libdir}pkgconfig/libnetfilter_queue.pc to find the libraries I don't imagine this is going to cause anyone any problems. If you want a hand adding options I'm happy to help.

4. small automake to install doco by default. Previous DOC= didn't do anything sorry.