as a rule, one should not rely on "using namespace xyz",
since this makes organisation of minimal header includes near impossible.
You end up with mass includes in some "top level" headers, resulting
in painfully slow compilation turnaround times.
In exceptional cases, using namespace foo might be adequate though
over time, a specific Lumiera code writing style has emerged.
The GUI, as it stood, used somewhat different conventions,
which now have been aligned to the common standard.
Basically we use GNU style, with some adjustments for OO-programming,
we prefer CamelCase, and write TypeNames uppercase, variableNames lowercase
the rules are:
- our own headers go before any library headers
- all headers need to be spelled relative to include root
- ensure that gtk is always included via gui/gtk-base.hpp
The pkg-config of GDL advises to include the GDL subdir,
which in turn contains a directory "gdl" with the headers.
This is fine, because it makes this name switch work
painless. Thus, please just #include <gdl/gdl-whatever.h>
