Jar-manifest

- added command line tool `read_manifest`:


usage: read_manifest [-h] [-r] JARFILE

Print a jar file's manifest as JSON.

positional arguments:
JARFILE jar file to read

optional arguments:
-h, --help show this help message and exit
-r, --recursive recurse into embedded jar files

- extended `manifest` function to recurse into embedded jar files

Initial release with rudimentary manifest-to-dict functionality.