stencil.scm: add make-path-stencil function

stencil.scm: add make-path-stencil function

supports all path commands both relative and absolute:
lineto, rlineto, curveto, rcurveto, moveto, rmoveto, closepath
also supports single letter syntax used in standard SVG path commands:
L, l, C, c, M, m, Z, z.
refactored make-connected-path-stencil for backwards compatibility and
continued use