Update .gitignore to ignore vim temporary files
Refactor build.xml, add JAR with no JavaHelp libs

* add a slim-jar ant target that will create a JAR archive with no embedded
  JavaHelp libraries, useful for Linux distribution package createors;
* add an example wrapper script to run the new jar by adding to the
  classpath the JavaHelp jar archive (using the current Debian path for it);
* general refactoring of the build file, now with less duplicated code and
  unnecessary build actions (e.g., no more creating HTML help files while
  running unit tests);
* add a separate applet-jar target, to avoid unnecessary signing of all the
  produced jar files;
* add new names for the jar targets: standalone-jar, cli-jar, debug-jar and
  the new slim-jar;
* set standalone-jar as the default target;
* update README.
Organize the source tree in a better way

* create the src/ directory, and move there all the source files;
* create the utils/ directory, with a few scripts and the (useless) key to use
  for applet signing;
* create the misc/ directory, where currently all the old tests lie;
* fix tests that would be broken by the move.
Regenerate the (useless) applet signing key
Build dir cosmetic fixes

* rename it from "edumips" to "build";
* ignore it in .gitignore;
* clean it up after tests.
Merge branch 'master' of https://github.com/lupino3/edumips64

Conflicts:
	readme