Change DIA: reference to IMG:
Move [IMG:8503 Stack trace generation] to separate file

The diagram is finalized, and having it in SVG allows to make it prettier.

Also, this means that now diff can detect differences in the XML SVG file.
Resize image
Add clarification in [DOC:8190 Exception class hierarchy]
Change base class of abc::buffer_error to abc::generic_error
Define abc::buffer_error without using macros
Rename abc::text_*error to abc::text::*error
Remove duplicate #include directive
Define abc::not_implemented_error without using macros
Define abc::security_error without using macros
Remove unused class abc::attribute_error
Define abc::key_error without using macros
Define abc::network_error without using macros
Define abc::network_io_error without using macros
Delete unused macros
Improve code documentation
Rename abc_throw() to ABC_THROW() to match macro naming convention
Reformat to 80 columns
Improve [DOC:8190 Exception class hierarchy]
Improve code documentation