Windows testing required: Updated runtime

I've put an interim build of pgAdmin 4 at https://developer.pgadmin.org/~dpage/pgadmin4-1.5-x86.exe for Windows users. This build uses a work in progress patch to replace the slow Qt components with ActiveQt + the Microsoft web browser control to significantly improve performance.

The version also includes close to 100 other bug fixes and changes, most noticeably performance improvements in the Query Tool that make it significantly faster than pgAdmin 3 with large result sets, and the ability to open the Query Tool and Debugger in new tabs that can be dragged onto different windows and therefore displays.

If you have the ability, please give it a test and let me know how it performs. There are some known issues that we're working on:

- The Query Tool History view isn't rendered correctly.

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