8 allium ls functional tests hang on windows

[kwalberg]

The changes here fix the language server test hang on Windows. The two issues were:

• istream::get() treats \r\n as a single character on Windows but two on Linux. Added logic to check for this case, which works on Windows and hopefully also works on Linux. The way I did it feels a little hacky, so not attached to it if you have a better solution.
• For some reason, serverProc.__exit__() was hanging instead of closing the process. Switching to terminate() plus some extra cleanup calls did the trick.

[kwalberg]

Looks like Linux tests are failing at the build step and Windows tests are being cancelled. Is that a branch-specific issue (and if so, any guess what's going wrong)? Edit: The same issue came up on the first build for the new branch, so looks like it's a general issue with the build.