Getting rid of static security initialization.

Both clazz.getClassLoader() and ClassLoader.getSystemClassLoader() check for RuntimePermission("getClassLoader") so both calls are now wrapped in a single PrivilegedAction if a SecurityManager is installed.

The remainder of the changes is related to the handling a null ClassLoader if that permission was not granted by the SecurityManager.
Added c'tor without cause-Throwable.
Handling of null ClassLoader.

This can only happen if RuntimePermission("getClassLoader") was not granted by an installed SecurityManager.
add ResourceExistsPropertyDefiner
Support attribute "optional" in include element

Support attribute "optional" in include element to prevent errors on
inclusion of non-existent files without requiring Janino and
FileExistsPropertyDefiner.
added diagrams explaining socketreceivers and co
removed OpenOffice draw locks
use the doAnchor class intead of span element
no need to nest the images within <a> element since they fit
make sure that all the 'view as groovy' links work, Gaffer does not support <receiver> at this stage, nor does the translator
LOGBACK-266 - allow max window size to be overriden
LOGBACK-266 - increase max window size of FixedWindowRollingPolicy to 20.  12 is too restrictive, and the users have voted for it to be increased
LOGBACK-835 - make timestamp properties default to local scope. Can be overriden by setting scope attribute
LOGBACK-833 - allow previously defined properties (in local scope) to be seen by SiftingJoranConfigurator
 * implemented part two of Ceki's suggestion
 * add getCopyOfPropertyMap() to the PropertyContainer and thus InterpretationContext
 * use local properties that are ineffect at time of creation of SiftingAppender to seed the properties map used when creting the child appenders and properties
 * removed some generics warnings
 * in AppenderFactoryBase use List.subList() rather than "copy whole array then delete and re-shuffle elements"
LOGBACK-835 - corrected status message in timestamp
LOGBACK-833 - unit test improvements to check that a local timestamp property really was set
correct ThreadPoolFactoryBean link to javadocs, correct typo in name of fieldsToCascade field in ComponentDelegate, added receiver function in ConfigurationDelegate (incomplete)
Merge pull request #110 from diroussel/LOGBACK-266

Fix for LOGBACK-266 - FixedWindowRollingPolicy MAX_WINDOW_SIZE too small
LOGBACK-246 implemented
clean up of section on custom converters