Fix compiler warnings for assigning NAN (float) to double
Fix compiler warnings for assigning NAN (float) to double

Use C++11 nan() function and generic NAN value (empty string)

https://en.cppreference.com/w/cpp/numeric/math/nan

dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin