Add config file support for ristsender and ristreceiver.

The file needs to be in yaml format, here is an example:

secret: blarg buffer: 0 encryption-type: 256 profile: <simple/main/advanced> stats: 1000 inputurl:

• ... outputurl:
• ... We used a built-in very simplistic native yaml parser and not a yaml library to not introduce a new dependency. The key-value pairs are the same ones used in the long-options of the command line (all are supported).

mentioned in commit 1c9757a2

merged