Updating readme

Updated JAVA url
cleaned up generated files and backup files
clean up temporary dir 'jar' and remove build result from source repo
removed do-git script
removed build result dir 'executable' from sources
removed dir 'debian'
simplified build script to create reprap.jar directly in executable dir
removed doc and nsis, man page, spurious scripts
clean up: removed uncommented code, formatted
Removed classes not needed for slicing
Clean up and simplification

* Removed RepRapException (was nowhere thrown)
* Removed interface Printer and GenericReprapPrinter
* Removed interface Extruder, NullExtruder and GenericExtruder
add executable directory again

it is the easiest way to distribute binaries via github
Removed file with wrong license.

ContinuationMessage.java and StatusMessage.java stated that they were
under a specific license which is not compatible with LGPL (as far as I
can tell, but IANAL).

Replaced the continuation dialog with a simple JOptionPane standard
dialog, removed usages of the status message dialog.
More clean up
removed .svn directories
removed unneeded libraries

* rxtx stuff will no longer be needed
* 3d libraries are not needed if java3d is properly installed
* cleaned old exclusion filters in .classpath
Mavenized project
fixed start script
set compiler level to 1.7
fixed error handling: fail fast