This was renamed to CATCH_REGISTER_ENUM in 541f1ed1 (Only provide
CATCH_REGISTER_ENUM, 2019-04-21).

This allows writing something like

  const auto v = calculateSomeVectorOfInts();
  CHECK_THAT(v, RangeEquals({1, 2, 3}));

Fixes #2915.

When presented with just '-' it would access the string at position [1]

This mirrors the changes done to the JUnit reporter in commit
fe483c056d9516d3550519c29fbf14a4d84d06d4

This is done by no longer requiring all assertions to be seen
by the JUnit reporter. Since the JUnit reporter never outputs
all assertions, even with `-s`, the only difference from storing
passing assertions in the `CumulativeReporterBase` was some
bookkeeping in deciding which sections are relevant to the output.

Given `TEST_CASE` that just runs many passing assertions, e.g.

```
TEST_CASE( "PERFORMANCE_TEST_CASE", "[.]" ) {
    for (size_t i = 0; i < 1000'000'000; ++i) {
        REQUIRE( i == i );
    }
}
```

the new JUnit reporter will finish in 5:47, using up ~7.7 MB of RAM.
The old JUnit reporter would finish in 0:30, due to bad_alloc
after using up 14.5 GB of RAM (the system has 16 GB total).

If the total number of assertions is lowered to 10M, the old
implementation uses up ~7.1 GB of RAM and finishes in 12 minutes.
The new implementation still needs only ~7.7 MB of RAM, and finishes
in 4 minutes.

There is a slight downside in that the output is slightly different;
the new implementation will include the `TEST_CASE` level section
in output, even if it does not have its own assertion. In other words,
given a `TEST_CASE` like this

```
TEST_CASE( "JsonWriter", "[JSON][JsonWriter]" ) {
    std::stringstream stream;
    SECTION( "Newly constructed JsonWriter does nothing" ) {
        Catch::JsonValueWriter writer{ stream };
        REQUIRE( stream.str() == "" );
    }

    SECTION( "Calling writeObject will create an empty pair of braces" ) {
        { auto writer = Catch::JsonValueWriter{ stream }.writeObject(); }
        REQUIRE( stream.str() == "{\n}" );
    }
}
```

the new implementation will output 3 `testcase` tags, 2 for the explicit
 `SECTION`s with tests, and 1 for the top level section.

However, this can be worked-around if required, and the performance
improvement is such that it is worth changing the current output,
even if it needs to be fixed in the future.

Closes #2897

This PR introduces a new `TEST_CASE` macro called `TEST_CASE_PERSISTENT_FIXTURE`. `TEST_CASE_PERSISTENT_FIXTURE` offers the same functionality as `TEST_CASE_METHOD` except for one difference. The object on which the test method is invoked is only created once for all invocations of the test case. The object is created just after the `testCaseStarting` event is broadcast and the object is destroyed just before the `testCaseEnding` event is broadcast.

The main motivation for this new functionality is to allow `TEST_CASE`s to do expensive setup and teardown once per `TEST_CASE`, without having to resort to abusing event listeners or static function variables with manual initialization.


Implements #1602

---------

Co-authored-by: Martin Hořeňovský <martin.horenovsky@gmail.com>

`max_digits10` is the number of decimal digits that the type _can_
represent, in other words, the number of decimal digits needed to
disambiguate any two floating point numbers when serialized to
a string.

The WithinRelMatcher does not listen to the precision specification; it just naively pipes to stringstream. If you specify the precision, that has no impact on the outputted values when the match fails.

This fix makes the WithinRelMatcher listen to the precision (https://github.com/catchorg/Catch2/blob/devel/docs/tostring.md#floating-point-precision) specified by: Catch::StringMaker<float>::precision