This prevents the glob from returning paths that don't include the root
template dir due to resolution of relative paths like `./foo`,
preventing #1541 from reoccurring. Furthermore, this prevents
misconfigured, non-existent template directories from silently passing
through, instead causing an error at init-time.
The directory structure has changed to better isolate crates serving
core and contrib. The new directory structure is:
contrib/
lib/ - the contrib library
core/
lib/ - the core Rocket library
codegen/ - the "compile extension" codegen library
codegen_next/ - the new proc-macro library
examples/ - unchanged
scripts/ - unchanged
site/ - unchanged
This commit also removes the following files:
appveyor.yml - AppVeyor (Rust on Windows) is far too spotty for use
rustfmt.toml - rustfmt is, unfortunately, not mature enough for use
Finally, all example Cargo crates were marked with 'publish = false'.