avoid expr(1), it is too funky

info expr includes:

    Strings are not quoted for 'expr' itself, though you may need
  to quote them to protect characters with special meaning to the
  shell, e.g., spaces.  However, regardless of whether it is
  quoted, a string operand should not be a parenthesis or any of
  'expr''s operators like '+', so you cannot safely pass an
  arbitrary string '$str' to expr merely by quoting it to the
  shell.  One way to work around this is to use the GNU extension
  '+', (e.g., '+ "$str" = foo'); a more portable way is to use '"
  $str"' and to adjust the rest of the expression to take the
  leading space into account (e.g., '" $str" = " foo"').

plus it only does BRE.
make sure all tests run pastish the same way

some tests didn't use exec, others didn't set HOME.
all tests have .pastish file

a bug in the CUT or the test could lead to the real curl(1)
getting used.  don't want.
generic form field support with pastish -o k=v

`pastish -o NAME=VALUE` submits with form field NAME set to VALUE
README markup changes

* placeholders in SYNOPSIS / DESCRIPTION use italics
* .Nm in SYNOPSIS, options in the DESCRIPTION are bold
* faux-literals are in backticks
* literals are simply in dquotes
GNUmakefile with a generalization through $(name)

makes the diffs between my hobby projects a tad smaller.
generalized summary