Feature request: do not overwrite built-in aliases by default

[tddschn]

aliases.ps1 removes powershell's built-in aliases, however, not all users would consider that behavior desirable.

One possible alternative is that
Import-Module git-aliases -DisableNameChecking doesn't remove those aliases silently
and only defines git aliases that doesn't conflict with the built-in ones,
and export a command, say Import-Conflict-Git-Aliases to remove built in aliases and set the previously conflicting ones.