Introduce support for Lua 5.2 and 5.3 in addition to the existing
5.1 support.

Version 2.7.0 of lrexlib removed the make based build system
and depends on luarock for building.

To avoid a dependency on luarocks (which is in testing) a custom
build was introduced.

make previous commits the upstream versions, and add few
additional fixes

Somehow expat-dev got a dependency on expat-doc. My guess
is that there was a previous bug/feature in abuild which
added the dependency.

Since abuild v2.22.0, these are removed automatically unless 'libtool'
option has been specified.