Add 1516e support to PGauge

[timpokorny]

Story

{As a} pgauge user,
{I want} a way to measure the performance of 1516e implementing RTIs,
{So that I can} compare them

Context

PGauge is currently based on HLA v1.3. Add support for completing the same tests, but with a 1516e interface rather than just a HLA v1.3 one.

Acceptance Criteria

Once complete, I shall be able to:

• Run a 1516e version of PGauge
• Choose between the 1.3 and 1516e varieties via command line argument