Re-implemented everything using ASP.NET.
Changed some requests to use JSON instead of FORM data.
Some work towards deleting the FIXMEGlobal instance.
Auth is missing, XSRF does not work correctly.
Add new filter syntax, prefixing with an "at sign"; i.e., `@...`, that
disables glob expansion, treating `*` and `?` wildcard characters as
literal characters.
In the GUI, change the restore file picker to prefix paths with `@`
when expanding a node to avoid mistaking literal `*` or `?` characters
for wildcards characters and triggering the following error:
```
Filter for list-folder-contents must be a path prefix with no wildcards Parameter name: filter
```
This fixes#4300.
Kenneth Skovhede