RD gateway not possible in mstsc mode #578

Describe the bug
If you check mstsc mode it is not possible to add settings for RD gateway

To Reproduce

1. enter settings for RD gateway
2. check mstsc.exe mode
3. possibility for RD gateway settings disappeared

Expected behavior
Should be possible to use RD gateway in mstsc mode

Screenshots

Desktop (please complete the following information):

• OS: Windows 10 Pro
• PRemoteM Version1.0.0 beta 7