Domain Parking Pro v3.7.5

Changed files:
- config.php
  - Version comment changed from v3.7.3 to v3.7.5.

- index.php
  - Portfolio URL now uses the current request protocol instead of hardcoded https.
  - Top brand/logo link now points to the current domain using the current protocol.
  - Related domain purchase links now use the current protocol instead of hardcoded https.
  - Offer form action was already protocol-aware and remains compatible with both HTTP and HTTPS.

- portfolio.php
  - Added current_scheme() detection.
  - Top brand/logo link now uses the current protocol.
  - Domain purchase links in the portfolio table now use the current protocol instead of hardcoded https.

Why:
- This prevents the script itself from forcing HTTP-only domains toward HTTPS.
- HTTP pages stay HTTP, HTTPS pages stay HTTPS.
- If a browser attempts HTTPS before it reaches the server, that is browser/SSL/DNS behavior and cannot be fully controlled by PHP.
