In v2 it was placed in a very central header due to the way it was
stitched together. Now that we don't do that, we can move it to the
proper place, removing the potential for confusion given that the
original header was split apart and renamed.
Previous splitting of catch_common.hpp left it containing only one
actual thing, which is the `SourceLineInfo` type. Given that, there
is no reason to keep the old name.
Also found out that it was included in some places for no reason
(primarily Matchers).
Lars Toenning
Martin Hořeňovský