Simplify and merge clean and shrink, into a standard format

This drops not-referenced entries, obsolete entries (as might be found from Launchpad imports), and standardizes equal entries into not-translated entries.
Hardcode the boundary
Drop the now-unnecessary option parsing
Merge TRANSLATED and DISTINCT, as "clean" now removes the distinction
Use Local::PO to parse and write, to keep formatting consistent
Move rt-message-catalog into devel/tools

There is no reason to install it; it is entirely a developer tool.
Update message catalogs
Standardize the order of PO attribute output, into what Locale::PO outputs
Update po files for #. prior to #: (as Locale::PO outputs)
Always drop strings which are no longer found in the source
Decode and encode as utf-8, to operate on characters
Allow "0" as a valid translation (however unlikely)
Quiet the display a little while parsing files for locstrings
Parse and output using Locale::PO; this simplifies the code considerably
Use Locale::PO to output locstrings; it splits multiline msgstrs across lines
Merge branch '4.2/message-catalog-updates' into 4.2-trunk