T_STRING is now const char * instead of char *

Fixes Guile constant wrappers removing -Wwrite-strings g++ warning.
Add missing #include <stddef.h> for offsetof when using -builtin.

Fixes SF #1345
Fix Visual Studio compile error in C++ wrappers due to #include <exception> within extern "C" block.

Fixes SF #1340
Fix unused variable warning in Ruby wrappers when using gcc -Wall
Fix gcc -Waddress warning in variables examples
Fix some gcc -Wall unused warnings in the Ruby wrappers

Fixes SF bug 1333.
Remove a couple of unused variable warnings in generated code
Correct guile help for -Linkage.

-linkage does not work (it clashes with the generic -l option).
Add feature director:except for improved director exception handling in Java

Closes #91
Code style conforming channges for Java director:except patch
Minor improvements to Java director:except patch
Remove pointless code from Java director:except patch
director:except tweaks Recode  whitespace handling, remove unnecessary comments in generated code.
directorthrows warning fixes

- Fix line number display - now the usual simpler warning message can be displayed
for WARN_TYPEMAP_DIRECTORTHROWS_UNDEF - it still points to the problem method.
- Use macro names for warning suppression in test.
More conventional variable naming in directorExceptHandling
Improve directorthrows patch

Separate $packagepath substitution from non-director code (as
documented). Some of the directorthrows code has been rewritten
so that fewer code changes are present compared to before the patch.

canonicalizeJNIDescriptor() refactored so it can be used for general
code, not just the directorin:descriptor typemap attribute.

Better implementation for substituting '$packagepath/$javaclassname' -
fixes some quirks in '$packagepath/$javaclassname' descriptor substitutions
if a dot was present in the descriptor string.
java_director_exception_feature_nspace test case changes

- The implementation for SEP for the classpath is not portable, eg the
separator should be ':' not ';' on Cygwin, but clearly it could be ';'
if using a native Windows version of Java. In the past the test-suite
has been constructed to avoid this problem and these changes go back to
this approach at the expense of not testing nspace without -package (but
not specifying -package is quite unusual when using nspace, so no great
loss). This test could be restored to how it was if the separator is
detected at configure time from the JVM itself, eg by calling Java code:

  System.out.println(System.getProperty("path.separator"));

- Mangle the non-public classes in the _runme.java file so that they are
unique to this testcase (the .class files generated can interfere with
other tests).

- Const corrections and spelling mistakes fixed in test case.

test case improvements
Cosmetics/code style conformance in newly added Java director exception handling
Rework the director.swg changes for director exception handling

- More robust implementation.
- Fix some bugs to give better exception messages when a user uses the
  director utility exception functions and classes.
- Replace unnecessarily shortened variable names for easier reading of
  code.
Changes file for recent director improvements