variety of fixes and a new script

variety of fixes and a new script

unpack gets to know a txz extension that is being erroneously created by chrome.  i can either resist the tide or just add this as a type of compressed (or maybe even uncompressed) tar, so i added it.

aliases for less, mo, more, etc get fixated to an actual function now.  otherwise the machinery being added gets too cumbersome.

new script is lesser which just runs less.  it supports a code option as -c if you want source highlighting.

variables get LESSOPEN taken away because not every file can be highlighted as source.  oh well.