escape all characters not allowed in XML tag names

escape all characters not allowed in XML tag names when creating the name-value-pairs for boost.

Allowed characters for tag names are upper and lower case characters, numbers and ".", ":", "-", and "_".
Now all other characters are mapped to "-" when creating the "name" part of the name-value-pair in the generated code. With this fix, templated class names can be written out into xml format (with the "conddb --dump" command).

Tested with the short matrix.