demos: ptext: added -textanchor
demos: added imagetint
demos: pimage: added -interpolation {none|fast|best} option
demos: pimage: -srcregion
demos: added example for pimage -width/-height and -fillopacity
demos: test linear gradient and -fillopacity
demos: added pimage: -anchor demo
demos: added gradientsalpha demo
demos: added imagealpha demo
demos: added arrowhead demos
change tkpath version to 0.3.3
demos: require tkpath 0.3.3
demos: fixes for run all.tcl