Changing error handling to throw runtime_error instead of string.

[markus-jehl]

No description provided.

[KrisThielemans]

Appveyor error was due to a bug introduced by myself. not sure why I hadn't seen it on Appveyor previously. It should be fixed in 63c2e9c

Please merge master in here (if the above commit worked). We'll also need some new release notes, but I wouldn't know what version to call it yet!

[markus-jehl]

Perfect, thanks. I merged master now. Will be away all of next week, so you have a bit of time to work out the version number ;-)

[KrisThielemans]

@markus-jehl can you please merge master again, and update the release_5.2.htm?

@evgueni-ovtchinnikov will this affect SIRF? (depends on how you catch STIR exceptions). Maybe you can check SIRF with this branch?

[markus-jehl]

Done! The failed test is because some server appears to have been down.

[KrisThielemans]

Great. I re-ran the job and it's fine. waiting for @evgueni-ovtchinnikov's input.

[evgueni-ovtchinnikov]

I found exactly one occasion of catch(std::string msg) in SIRF and replaced it with catch(…), so I do not expect any SIRF problems with this PR merged.

[KrisThielemans]

thanks @evgueni-ovtchinnikov