to avoid using namespace at global scope

[offspring]

adding using directive in header files is not a good idea, with this PR

this code

            if(!config.containsKey(str)) {
                debugE("N2kFluidLevelSender: Missing configuration key %s",
                       str.c_str());
                return false;
            }

will not require

using namespace sensesp;`

in the include files

https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#sf7-dont-write-using-namespace-at-global-scope-in-a-header-file

[mairas]

Good catch!

In the dev-3 codebase, I've taken a bit different approach with the logging/debugging macros: ESP-IDF native ESP_LOGx macros are used as is. The debugX macros are still provided for backwards compatibility - and actually, most of the codebase still uses them. Probably should do a cleanup before the release.

It would be great if you'd have time to do a similar PR against the dev-3 branch as well. But if not, that's OK, the change is pretty simple.