Use -std=c++14 (instead of c++11). Pointers how to integrate with
pkg-config for non-CMake projects.

catch_default_main.hpp was removed in db32550898

The example 000-CatchMain.cpp is no longer compiled, but is still
present in the examples and is still references by other example
files. Remove the file and references to it, as they are confusing.

By not materializing the lower cased tags ahead of time, we
save allocations at the cost of worsened performance when comparing
two tags.

Since there are rarely many tags, and commonly they are not
compared even if present, this is almost always a win. The new
implementation also improves the robustness of the code
responsible for handling tags in a case-insensitive manner.

Note that only documentation and comments are impacted by this change.

The base was also renamed from `TestEventListenerBase` to
`EventListenerBase`, and modified to derive directly from the
reporter interface, rather than deriving from `StreamingReporterBase`.

Each of the two reporter bases now has its own header file, and
cpp file. Even though this adds another TU to the compilation,
the total CPU time taken by compilation is reduced by about 1%
for debug build and ~0.5% for optimized build of the main library.
(The improvement would be roughly doubles without splitting the TUs,
but the maintainability hit is not worth it.)

The code size of the static library build has also somewhat decreased.

Follow up: Introduce combined TU for reporters, and further split
apart the catch_reporter_streaming_base.hpp header into its
constituent parts, as it still contains a whole bunch of other stuff.