v1.5.0: SJTUBeamer min + max + max-plus!

SJTUBeamer 1.5.0 is a collaborative work of previous SJTUBeamer by @sjtug and SJTUBeamermin by @LogCreative. In SJTUBeamer 1.5.0, we added a lot of new themes. We are continuously working on this new release of SJTUBeamer to add documentation, usage guides, and more examples.