Feature/mac dmg

clang failed to compile cross_match because the code uses
"empty" return in a non-void context. GCC does no die on this
warning but it takes a very long time to compile.
By using -Wno-return-type in make, clang can compile cross_match.

gcc8 can compile cross_match
Compiling gcc8 with libunwind-headers causes problems, we need to make
sure the library is not present

cross_match is under license so we cannot distribute a dmg with
cross_match to anyone. The default is not to add cross_match

The tarball downloaded from the Sanger FTP has a different name

Added usage
Added options to specify the different directories
Create image base on otter version and MACOSX_DEPLOYMENT_TARGET

We use percona for our mysql libraries. The binaries use almost 200MB
but they are not needed

If ZMap is built with mysql support, it can use the EnsC API to connect
directly to any Ensembl database

The extra_cflags was hard coded. Here the code is trying to set it up
based on the machine in it run on. If MACOSX_XCODE_PATH and
MACOSX_DEPLOYMENT_TARGET are set in the terminal, the values will be
used.

The test fail on some encoding test which is not supporting by newer
Perl anymore. It should not cause problem but it would be better for
the tests to be fixed

If Perl doesn’t work anymore, we might need to revert this change

The kent library is taking a lot of useless disk space in our case. We
only want jkweb.a and the header files

For some reasons BioPerl has been submitted by someone else so either
we will have to use a different regex or maybe use git to get BioPerl

Use the prefs files to add library info to the modules

This is not great but the test failing are about vcf and leaks. I do
not have the time to check the problems now

Use arguments instead of environment variable

TODO
add proper options to set some variables

If Zircon is tested, it will be stuck in some context. The build is
unlikely to fail but it would be better to try to find the real reason,
fix it and do the test

In newer versions of perl, if you use or in a return statement, the
right side of the statement is not evaluated. It needs ||

We do not need python or latest version of perl. They are removed with
their dependencies. We cannot do python27 because it would remove gtk
which we need

Config::IniFiles needed an old hacked version. According the ticket URL
in README.perl_by_hand, the issue is fixed in that latest version

It is not great and can be reverted when a proper solution is ready.