Add-Reads and Add-Modules manifest attributes?

[Andrew Guibert]

I was happy to see that a resolution was reached for #AddExportsInManifest,
but why did this stop at Add-Exports and Add-Opens?  In order to cover all
use cases (for unnamed modules), we would need two more manifest
attributes:

# Equivalent to: --add-reads=java.base=ALL-UNNAMED
--add-reads=java.sql=ALL-UNNAMED
Add-Reads: java.base, java.sql

# Equivalent to --add-modules=java.se.ee
Add-Modules: java.se.ee

Based on my experience with JPMS so far, manifest attributes are a much
cleaner way of specifying the JPMS workaround options.  Mainly because on
older JDKs they are silently ignored so I don't have to add conditionally
apply the new Java 9 args in my launch commands.

- Andy