add missing global $db ref
modulemanager: errormessage and module loading

add a message if a module cannot be loaded;
more robust error messages: allow string (modulename) aswell.
content/admin: show error messages

..such as when no permission to edit.
lib/Debug: show timestamps since request start
lib/XML: XSLT caching update (XSLT disabled!)

re-using XSLTProcessor under certain circumstances
will simply close the HTTP connection.
Updated the caching to at least cache the DOMDocument of the XSL,
thus preserving at least the merged stylesheets (and the initial PSP XSL
application).
XSLTProcessor cache is currently disabled. When enabled however,
the registerFunctions and setParameters are called again to update
and/or register any new information (since a sheet that is applied
a second time later on will likely be for different content).
ModuleManager: allow parameterized modules

lib/ModuleManager.php:
	add $args to loadModule;
	add debug;

psp/psp.php:
	module(): add $args and check for correct type;

psp/psp.xsl:
	add 'psp:module' tag; nested XML is passed on to the psp_module
	function.
serve.php: append timing in XML comment
add SQL information_schema meta; add tmp resource

lib/Resource.php:
	add a 'tmp' DirectoryResource, retrievable with:

		 $tmpdir = DirectoryResource::findFile( "", 'default', 'tmp' );

lib/db/meta.php:
	some information_schema queries for MySQL and PostgreSQL
	with some pg_* extensions for table inheritance.
add lib/db/pdo.php PDO wrapper