Rename crate source filenames to standard ones.

 * Don’t use ‘.rc’ file extension.
 * Use ‘main.rs’ for executables.
 * Use ‘lib.rs’ for libraries.
Rename crate source filenames to standard ones.

 * Don’t use ‘.rc’ file extension.
 * Use ‘main.rs’ for executables.
 * Use ‘lib.rs’ for libraries.