Portable dynamic library loading for Guile

dynamic-link and load-extension work without passing the .so or .dll as
the shared library extension, so these have been dropped so the examples
and test-suite work on Cygwin.

Also update documentation and use the 'lib' prefix as that is what we
commonly name the shared libraries.

Doc/Manual/Guile.html

@@ -115,7 +115,7 @@ libraries into Guile.</p>
 <div class="targetlang">
 <pre>
 (define-module (my module))
-(define my-so (dynamic-link "./example.so"))
+(define my-so (dynamic-link "./libexample.so"))
 (dynamic-call "SWIG_init" my-so) ; make SWIG bindings
 ;; Scheme definitions can go here
 </pre>
@@ -128,7 +128,17 @@ and <code>dynamic-call</code>:
 
 <div class="targetlang">
 <pre>
-(load-extension "./example.so" "SWIG_init")
+(load-extension "./libexample.so" "SWIG_init")
+</pre>
+</div>
+
+<p>
+A more portable approach would be to drop the shared library extension:
+</p>
+
+<div class="targetlang">
+<pre>
+(load-extension "./libexample" "SWIG_init")
 </pre>
 </div>
 
@@ -171,7 +181,7 @@ information by including a directive like this in the interface file:
 
 <div class="code">
 <pre>
-%scheme %{ (load-extension "./example.so" "SWIG_init") %}
+%scheme %{ (load-extension "./libexample.so" "SWIG_init") %}
 </pre>
 </div>
 
@@ -225,7 +235,7 @@ shared libraries into Guile; all bindings are automatically put in
 newly created Guile modules. 
 <div class="targetlang">
 <pre>
-(define my-so (dynamic-link "./foo.so"))
+(define my-so (dynamic-link "./libfoo.so"))
 ;; create new module and put bindings there:
 (dynamic-call "scm_init_my_modules_foo_module" my-so) 
 </pre>
@@ -233,7 +243,7 @@ newly created Guile modules.
 Newer Guile versions have a shorthand procedure for this:
 <div class="targetlang">
 <pre>
-(load-extension "./foo.so" "scm_init_my_modules_foo_module")
+(load-extension "./libfoo.so" "scm_init_my_modules_foo_module")
 </pre>
 </div>
 </ul>
@@ -768,10 +778,10 @@ and might conflict with names from the GOOPS guile-module (see above).  Pass the
 argument to solve this problem.  If the <code>-exportprimitive</code> option is passed to SWIG the
 <code>(export ...)</code> code that would be exported into the scmstub file is exported at the bottom 
 of the generated GOOPS guile-module.
-The <code>%goops</code> directive should contain code to load the .so library.
+The <code>%goops</code> directive should contain code to load the shared library.
 
 <div class="code"><pre>
-%goops %{ (load-extension "./foo.so" "scm_init_my_modules_foo_module") %}
+%goops %{ (load-extension "./libfoo.so" "scm_init_my_modules_foo_module") %}
 </pre></div>
 
 <p>
@@ -783,7 +793,7 @@ Produces the following code at the top of the generated GOOPS guile-module
 (define-module (my modules foo))
 
 ;; %goops directive goes here
-(load-extension "./foo.so" "scm_init_my_modules_foo_module") 
+(load-extension "./libfoo.so" "scm_init_my_modules_foo_module") 
 
 (use-modules (oop goops) (Swig common))
 </pre></div>
@@ -791,7 +801,7 @@ Produces the following code at the top of the generated GOOPS guile-module
 
 <li><p><b>Passive Linkage with -scmstub</b>: Here, the name of the scmstub file should be
 <code>Module-primitive.scm</code> (with <i>primitive</i> replaced with whatever is given with the <code>-primsuffix</code>
-argument.  The code to load the <code>.so</code> library should be located in the <code>%scheme</code> directive, 
+argument.  The code to load the shared library should be located in the <code>%scheme</code> directive, 
 which will then be added to the scmstub file.
 SWIG will automatically generate the line <code>(use-modules (<i>Package</i> <i>Module-primitive</i>))</code>
 into the GOOPS guile-module.  So if <i>Module-primitive.scm</i> is on the autoload path for guile, the
@@ -799,7 +809,7 @@ into the GOOPS guile-module.  So if <i>Module-primitive.scm</i> is on the autolo
 whatever code is needed to load the <i>Module-primitive.scm</i> file into guile.</p>
 
 <div class="targetlang"><pre>
-%scheme %{ (load-extension "./foo.so" "scm_init_my_modules_foo_module") %}
+%scheme %{ (load-extension "./libfoo.so" "scm_init_my_modules_foo_module") %}
 // only include the following definition if (my modules foo) cannot
 // be loaded automatically
 %goops %{ 
@@ -832,7 +842,7 @@ SWIG will also automatically generate the line <code>(use-modules
 directive should contain whatever code is needed to get that module loaded into guile.</p>
 
 <div class="code"><pre>
-%goops %{ (load-extension "./foo.so" "scm_init_my_modules_foo_module") %}
+%goops %{ (load-extension "./libfoo.so" "scm_init_my_modules_foo_module") %}
 </pre></div>
 
 <p>
@@ -843,7 +853,7 @@ Produces the following code at the top of the generated GOOPS guile-module
 (define-module (my modules foo))
 
 ;; %goops directive goes here (if any)
-(load-extension "./foo.so" "scm_init_my_modules_foo_module") 
+(load-extension "./libfoo.so" "scm_init_my_modules_foo_module") 
 
 (use-modules (oop goops) (Swig common))
 (use-modules ((my modules foo-primitive) :renamer (symbol-prefix-proc