The issue is with "dllexport": previously, dllexport was present on
exposed templates tool (= visibility(default) for gcc/clang). This
ensured MacOS compatibility since then the typeinfo is corretly
shared and dynamic_cast/typeid works.
For Windows, the "dllexport" equivalent requires the template
instantiations to be declared "external" which is a coding nightmare.
The solution is to provide separate macros for real (non-specialized,
not explicitly instantiated) templates (.._PUBLIC_TEMPLATE) which
is defined as empty for Windows and "visiblity(default)" for gcc/clang.
This enables font packages: packages can now provide fonts by
featuring a "fonts" directory with the font layouts.
This commit also adds the capability to dynamically add fonts.
The Glyphs system is decoupled from the application's system
path and the BASIC.TEXT PCell parameters are non-cached to
enable dynamic updates.
Matthias Koefferlein