Handling enums as cmdlet parameters.

Summary of the new feature / enhancement

Changing the handling of enums as cmdlet parameters uses to display the possible values the values of the enum and the get the name for the value. Therefore xou get the same text if more than one name has the same value (see example below).

Proposed technical implementation details (optional)

<#
Display option when using an enum as a parameter of an CmdLet.
#>

Enum TestAction
{
Ignore = 0
Skip = 0
Replace = 1
New = 1
Remove = 2
Detete = 2

} # Enum TestAction

Function Test-Enum
{
param
(
[Parameter( Mandatory )]
[TestAction]
$Action
)
<#Do something#>

} # Function Test-Enum

<#
If you enter on a prompt
Test-Enum -Action
and try to select an action you get the following sequence:
Ignore
Ignore
Replace
Replace
Remove
Remove
Ignore
It would be nice to get the alias names as well.
Use [enum]::GetNames() instead [enum]::GetValues().
#>

Start with issue #396 and reproduce the enum cmdlet parameter completion example using duplicate enum values. Investigate the parameter-completion entry point that currently obtains enum values, then verify that completion exposes each name, including aliases such as Skip, New, and Detete, without duplicate value-based suggestions.