Text 1.5.)

This change isolates initialization logic into a new
ThrowableProxyHelper class, and rendering logic
into ThrowableProxyRenderer.

Both new utility classes are package private. ThrowableProxy public
API has not changed.

RollingRandomAccessFileAppender.

Proxies through several interfaces in order to simulate performance
of a standard application, which doesn't benefit quite as much
from the ThrowableProxy Map<String, CacheEntry> cache.

Initial results:

Benchmark                                                            Mode  Cnt       Score       Error  Units
FileAppenderThrowableBenchmark.complexLog4j1                        thrpt    3    8562.548 ±  4122.961  ops/s
FileAppenderThrowableBenchmark.complexLog4j2ExtendedThrowable       thrpt    3    2575.655 ±   218.395  ops/s
FileAppenderThrowableBenchmark.complexLog4j2ExtendedThrowableAsync  thrpt    3    2518.260 ±   335.573  ops/s
FileAppenderThrowableBenchmark.complexLog4j2Throwable               thrpt    3   12738.874 ±  2867.140  ops/s
FileAppenderThrowableBenchmark.complexLog4j2ThrowableAsync          thrpt    3    3489.965 ±   471.234  ops/s
FileAppenderThrowableBenchmark.complexLogbackFile                   thrpt    3   12866.339 ±  1396.160  ops/s
FileAppenderThrowableBenchmark.julFile                              thrpt    3   55019.426 ±  9342.755  ops/s
FileAppenderThrowableBenchmark.log4j1                               thrpt    3   75444.252 ± 18508.319  ops/s
FileAppenderThrowableBenchmark.log4j2ExtendedThrowable              thrpt    3   45708.853 ± 13553.851  ops/s
FileAppenderThrowableBenchmark.log4j2Throwable                      thrpt    3  110923.511 ± 19661.868  ops/s
FileAppenderThrowableBenchmark.logbackFile                          thrpt    3  112548.025 ± 40720.422  ops/s

This closes #203

make ReusableObjectMessage always pass its object as the first parameter

This closes #205

Standardize forkCount on 1, rather than 2*CORES.

log4j-core uses one fork which is not reused. Most of our time
spent in tests is running those in log4j-core. Applying this
configuration to all modules prevents test flakes.

Share the SecurityManager implementation of getCurrentStackTrace
with the java 9 implementation.

Revert "Add low-level method org.apache.logging.log4j.core.appender.AsyncAppender.getThreadQueueSize() to help synch tests in applications."

This reverts commit 1927dfa7.

org.apache.logging.log4j.core.appender.AsyncAppender.getThreadQueueSize()
to help synch tests in applications.

mongo tests intermittenly fail with an "Operation not permitted"
IOException when trying to execute the mongod extracted by
de.flapdoodle.embed.process; this seems to be related to surefire
running tests in parallel. Work around that here by forcing serial
execution of the mongo tests.

This closes #201

When emptyReplacement length is less than 10 but large enough for
the current paramers, the ReusableParameterizedMessage would
retain references to the most recently logged parameters.

This closes #200

Combine codepaths for initial and terminal fragments.
Add changelog entry.

This closes #188

session logger failed (Closes #198).

Regression introduced here, removing StackLocator.SECURITY_MANAGER
initialization: 55b9fd20

Removed a few  unnecessary parameters and operations.

ExtendedThrowablePatternConverter no longer constructs a String
of the full stack trace, instead appending to the layout
StringBuilder.

This does not provide any benefit for
ExtendedThrowablePatternConverter.

Updated Benchmarks:

Benchmark                                                Mode  Cnt       Score       Error  Units
FileAppenderThrowableBenchmark.julFile                  thrpt    3   42411.701 ±  9740.338  ops/s
FileAppenderThrowableBenchmark.log4j1                   thrpt    3   58608.053 ±  9127.229  ops/s
FileAppenderThrowableBenchmark.log4j2ExtendedThrowable  thrpt    3   15443.610 ±  3942.549  ops/s
FileAppenderThrowableBenchmark.log4j2SimpleThrowable    thrpt    3  114443.966 ± 29211.657  ops/s
FileAppenderThrowableBenchmark.logbackFile              thrpt    3  135646.780 ± 16794.353  ops/s

Initial results (re-ordered fastest to slowest):

Benchmark                                                Mode  Cnt       Score       Error  Units
FileAppenderThrowableBenchmark.logbackFile              thrpt    3  135260.838 ± 15790.010  ops/s
FileAppenderThrowableBenchmark.log4j2SimpleThrowable    thrpt    3   87385.712 ±  8082.803  ops/s
FileAppenderThrowableBenchmark.log4j1                   thrpt    3   60359.485 ± 10122.858  ops/s
FileAppenderThrowableBenchmark.julFile                  thrpt    3   52134.431 ±  1302.365  ops/s
FileAppenderThrowableBenchmark.log4j2ExtendedThrowable  thrpt    3   15348.378 ±  1301.501  ops/s