painless

This makes sure that we do not overwrite the parameter file in cases where the same process has already created a parameter of the same name. This allows us to share parameters across scopes / threads. closes #2

We probably need to make sure that parameter names are unique. In a single scope, this is enforced by the compiler. However, nothing is currently preventing the user to create multiple parameters with the same name in different scopes. We would probably need a central "parameter library" class (singleton?) that keeps track of all registered parameters.

While you can always assume to be available, POSIX mandates that you check the environment variable as a preference for temporary files and directories [1]. For the minor improvements: might fail and has to be handled somehow. I chose to throw an exception, but an implementation where you fall back to [2] is also conceivable. A lot of the specialization for function templates are not needed. They can just be replaced by regular overloads. An was missing, possibly leading to linkage problems. [1] https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap08.html#tag_08_03 [2] https://linux.die.net/man/3/tmpfile