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Description

In order to support moving to using a spawn like interface for calling git commands in a subprocess (rather than backticks), make the following changes to Git::Lib#command:

• Collapse the cmd parameter and the opts parameter into a single Array parameter named cmd
• Do not allow the cmd parameter to have nested arrays. Enforce that it is an Array of Strings only by raising an ArgumentError when cmd is anything other than an Array of Strings.
• Options that apply to how #command works (and are not passed on to the git command like redirect and chomp) should be passed as keyword parameters to #command instead of a Hash at the end of the cmd / opts Array parameter.

These changes impact both the implementation of Git::Lib#command as well as its callers.