Merge pull request #16 from keithj/devel

Sync devel with master
Build Perl wrappers.
Merge pull request #17 from keithj/devel

Build Perl wrappers
Removed Perl targets from default targets because the object files
are build with flags that conflict with the main build.

Use CXX in preference to CC

Respect user-provided CXXFLAGS
Merge pull request #18 from keithj/devel

Fix for building with/without Perl wrappers
Merge changes from wtsi-npg devel