Add pathname config option, revert readonly switch/default settings

[slvrtrn]

Summary

Into 1.0.0.

• Added pathname config option, as after Add support for URL parameters parsing #232 we could have Don't override pathname in transformUrl #207 issue again.
• Base and URL configs are now "deep merged" instead of overriding only the top-level key.
• Reverted Add default HTTP settings + readonly user switch #225: as the HTTP module has a header size limit (in my tests, around 76 progress headers), it is unsafe to enable it by default. Documentation and examples should already cover these long-running query use cases.
• Disabled compression.response by default; it was unclear what client option was causing issues with queries performed by the readonly=1 user when using the client without additional configuration.
• Added more advanced example on possible "hacks" with long-running queries based on our discussion in What is the best way to trigger a command and polling until is done by query_id? #244
• Updated JSDoc for the config options.
• Adjusted changelog accordingly.

Checklist

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG

[mshustov]

The next time, I'd suggest splitting unrelated changes into 2 separate PRs to simplify the code review