Ideas to simplify templates

I have a few suggestions regarding templates:
- **Move bundled templates out of the source code.** They could be included from a resource file/folder, which should also work from inside a package (WRT #31).
- **Only one template per file.** Each template's name is derived from its filename by removing the file extension (or using no file extensions at all). No need to parse the name from its content.
- **Simplify image serialization.** Get rid of JSON, square brackets, commas. Only one byte per "pixel", newslines as row delimiters, and no other whitespace. Numbers 0-4 as well as the ASCII representation work with that. Would greatly simplify parsing as well as template creation.