* Paths defined via pcbnew->Preferences->Configure Paths are now included in
the 3D file browser's drop-down list except for KICAD_PTEMPLATES, KIGITHUB,
KISYSMOD, any paths resembling a URL, and any non-existent paths. When an
absolute path is shortened using one of these path aliases, let's say
'KISYS3DMOD' then the name appears in the pcb file as "${KISYS3DMOD}/blah.wrl".
If a user defines and actual environment variable with the same name, then
that user defined variable will have precedence over the internally defined
variable.
* Paths relative to the current project directory are no longer represented
as "some/path/to/file.wrl". For compatibility with previous KiCad versions
it shall always be stored as ${KIPRJMOD}/some/path/to/file.wrl.
* Various restrictions on alias path values have been removed since the
imposed restrictions could result in corrupted user data as aliases are
silently dropped.
* Overall the patch should improve back-compatibility by providing a ${ENV_VAR}
mechanism for supporting different model root directories and ensuring that
paths relative to KIPRJMOD are expressed in a way that is compatible with
earlier KiCad versions. This allows users more flexibility and the ability
to work in a way that ensures 3D model files can be correctly resolved in
earlier versions of KiCad. Users who do not care about back-compatibility
may prefer to use the newer alias system.
The attached patch fixes a segfault due to a race condition.
If a user starts eeschema with an empty sheet and clicks
the 'cvpcb' button, memory is corrupted and the program
segfaults. The issue appears to arise from multiple threads
accessing the 3D cache and resolver. This patch makes
relevant code thread-safe by using a wxCriticalSection.