api export: Dynamic export of highlighting functions
api export: Dynamic export of filetypes functions
api export: Dynamic export of navqueue function
api export: Dynamic export of editor functions
api export: Dynamic export of plugin functions
api export: Dynamic export of main functions
api export: Dynamic export of stash functions
api export: Dynamic export of symbols function
api export: Dynamic export of symbols function
api export: Move deprecated geany_functions to separate file.

This makes the deprecated status more explicit and later removal more easily
while also making it harder to accidentally extend it.
api export: Remove HAVE_PLUGINS guard in pluginutils.h

This header is now used by plugins themselves as well, which don't usually
define HAVE_PLUGINS. Remove this guard which isn't present in other headers
that contain exported functions either.
DO NOT MERGE dllexport scintilla
WIP