Moving the Unpacking functionality in its own class (+ important bug fix with sorting priorities)
tidy and critic improvements to unpack
 switching to using Core::Unpack; adding documentation
 perltidy on LaTeXML.pm
 making pre-commit aware of files with both staged and unstaged changes; focus only on the staged file
 mocing Unpack to the Util namespace
 auto-vivify destinations for archive whatsouts so that the main XML file can be written
 removing redundant check of whatsout
invent a name when whatsout archive requested on stdout
relax defensive destination checks when whatsout is archive
moving Post::Pack to Util::Pack
 merging unpacking and packing features for archives in Util::Pack
 oops, forgot to migrate File::Path import
Merging the Pack/Unpack refactoring to Util