When using the "old" syntax for Paket commands, such as paket add nuget <package>, Paket shows a warning saying

Please use the new syntax: nuget -> (omit, option is the new default argument)

or

Please use the new syntax: project -> --project

These are concise but not very friendly, and the first one requires some interpretation to make sense of.

This PR makes these messages more human-readable:

Please use the new syntax: 'nuget' is the default argument and should be omitted.

and

Please use the new syntax: 'project' has been replaced by '--project'.

Also, the error message when using old and new syntax together has been changed from

You cannot use the old and new syntax at the same time: project <-> --project

to

You cannot use the old and new syntax at the same time: 'project' has been replaced by '--project'. You cannot mix the two.