TLS default config is never freed

[ghost]

I think the TLS API default configuration is never freed. Also I don't see how the user can access the default configuration in order to have control upon it.

tls_free is related to the context. I think if there is tls_init, there should be tls_free which frees the global config allocated and other things global. But tls_free is related to the context, thus, its name should be like tls_ctx_free().. for me is confusing. In general I think API funcitons related to the context to have name like tls_ctx_...

Also I think the pointer arguments like ctx and others of the api functions should be checked if they were provided by the user as NULL, thus it will make the use of API functions more secure.