improved ability to save and load app window size and location

[mega5800]

:+1::tada: First off, thanks for taking the time to contribute! :tada::+1:

Please fill out the following checklist:

• [ ] Added tests for any bug fixes that changed existing code
• [ ] Added tests for any new behavior
• [ ] All unit tests are passing (please make sure all tests are passing for your branch/PR at https://ci.appveyor.com/project/activescott/lessmsi/history )

If you need any help at all, feel free to submit the PR and @-mention activescott and I'll be happy to assist!

Hello @activescott

I took care of this ticket. Instead of using lessmsi-gui.exe.config for size and location settings, the app now saves them in the same way as RecentFiles setting.

I tested the final result, and was able to use lessmsi-gui.exe in C:\Program Files folder. I didn't get any permissions errors after closing the app.

Thank you.