Updates README.md
Updates help message
Adds more presets, fixes bugs
Adds '--model-used' option
Updates API KEYs management
Updates support code for dump server
Add count of cached tokens
Add support for dump server such as httpbin.org
Add api-key name can be customized
Update CHANGELOG.md
Removes duplicate code for JSON output
FIX 'nil pointer dereference' if format is JSON
Update README.md