- Also removed "crop" from Clip class, as it was never implmeneted correctly, and we have a fully functional "crop" effect when needed
- Added caching to Clip class, to optimize previewing of cached frames (much faster than previous)
- Replacement method names are SetParentClip/GetParentClip
- Old names are retained as deprecated alternates, for now
- libopenshot internal calls (very few) are updated
ReaderBase.cpp: Remove (Set,Get)Clip
- Parsing from string to Json::Value is now done by utility function
openshot::stringToJson() in Json.cpp, all SetJson() methods call it.
- Expand use of const member functions and args where appropriate.
- Use std::to_string() to format int/float values as strings.
- Correct mentions of nonexistent Json::JsonValue type in docstrings
This changes the type of the private `path` variable to QString
internally (which we were converting it to for a bunch of operations
anyway), and uses QString's more robust string-manipulation and
comparison methods to ensure that only filenames that _end in_ an
.svg/.svgz extension (case-insensitively) are recognized as SVG files.
Previously, a filename such as "Title.svg.png" would be interpreted as
an SVG file.
The change in QString type is purely internal, all of the class's
interfaces remain the same, and accept `std::string path`. We simply
convert it to/from QString at opposite places in the code, now.
