Missing documentation for Max index limit in DefaultRolloverStrategy.

LOG4J2-1858 refactor existing places that trim a StringBuilder to max size to use the StringBuilders utility method

LOG4J2-1858 ensure ThreadLocal StringBuffer won't hold excessively much memory after logging a long message, also fix Math.min -> Math.max bug

LOG4J2-1858 ensure ThreadLocal StringBuffer won't hold excessively much memory after logging a long message

# Conflicts:
#	src/changes/changes.xml

Builds OK locally with 'mvn clean install' and Apache Maven 3.5.0
(ff8f5e7444045639af65f6095c62210b5713f426; 2017-04-03T12:39:06-07:00)
Maven home: C:\Java\apache-maven-3.5.0\bin\..
Java version: 1.7.0_80, vendor: Oracle Corporation
Java home: C:\Program Files\Java\jdk1.7.0_80\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 8.1", version: "6.3", arch: "amd64", family: "windows"

Builds OK locally with 'mvn clean install' and Apache Maven 3.5.0
(ff8f5e7444045639af65f6095c62210b5713f426; 2017-04-03T12:39:06-07:00)
Maven home: C:\Java\apache-maven-3.5.0\bin\..
Java version: 1.7.0_80, vendor: Oracle Corporation
Java home: C:\Program Files\Java\jdk1.7.0_80\jre
Default locale: en_US, platform encoding: Cp1252
OS name: "windows 8.1", version: "6.3", arch: "amd64", family: "windows"