Feature request: Read config defaults from a config file

What comes below is a suggestion/feature request.

# What
Read config defaults from a config file (put somewhere in the home root, like `~/.restview.ini`.

# Why
Put (most or at least most-common) of the configuration options in there.

For instance, I use this project from time to time and don't want to memorize all the options (to avoid opening a browser window each time). Instead, I want to configure it once and use it.

Start by locating how restview currently defines and parses its command-line configuration options; the issue does not name a file or test. The work is done when commonly used options can be read as defaults from a home-directory config file such as ~/.restview.ini, while command-line values still work as intended.

Written by the indexing model from the issue text.