implement RFC98 (#4673) and  RFC99 (#4704)

- implement complex scrit shaping via harfbuzz
- refactor text rendering pipeline
- remove support for GD renderer
- remove support for deprecated annotation layers
update my email
add RFC103 layer->encoding implementation (#4758)
update HISTORY.TXT for major 7.0 features
RFC104: Use embedded truetype font instead of BITMAP labels (#4759)