Fix name collision with read_url in SolveIt

[algal]

The problem is reported and illustrated here: https://discord.com/channels/1303610061167263814/1310989166875508849/1413524901393858621

The problem is:

• SolveIt also defines a function read_url as a tool
• ContextKit defines a tool read_url and exports it, so users will pick it up if they from contextkit import *
• So there's a name collision.

Remedies:

• rename ContextKit.read_url (breaks backward compatibility)
• and/or: add fancy import behavior to ContextKit, so that ... what?
  • ifread_url is already defined, then it prints a warning about the conflict and alerts the user the name has been changed? This would help SolveIt users, who will have SolveIt's read_url already defined.
  • something else?