src_clean, copyrights
"allows to" -> "allows one to"
fix compilation with shared libs

Some libraries required when building GenomeTools using shared
dependencies were not added in the linker call, leading to
problems later on. Examples: libm, libpthread.
disable use of xmllint for manpage generation

This fixes some weird issue when building Debian packages.
make public symbols list creation more portable
src_clean
update documentation
Merge pull request #305 from satta/smallfixes

Small fixes