Wapp

The documentation mentions that if you want to be able to `package require wapp` directly, you should build `wapptclsh`. However it's also very easy (and I would argue very useful) to set up wapp to be directly compatible with vanilla `tclsh`. If you put a `pkgIndex.tcl` file in the root dir with the following contents:

`package ifneeded wapp 1.0 [list source [file join $dir wapp.tcl]]`

... and make sure the root dir is directly or indirectly in [auto_path](https://wiki.tcl-lang.org/page/auto_path), wapp will act as a normal Tcl package.

If you put the `pkgIndex.tcl` file and the following `testwapp.tcl` file inside the root dir:

    lappend auto_path [file dirname [info script]]
    
    package require wapp
    
    proc wapp-default {} {
      wapp-subst {<h1>Hello, World!</h1>\n}
    }
    wapp-start $argv


You can get a "Hello World" page with just `tclsh testwapp.tcl`. If you install wapp as a system-wide library you won't need to touch the `auto_path` at all, this is just done for testing purposes here.

Adding a `pkgIndex.tcl` file would make wapp's usage identical to that of other Tcl packages like the ones in Tcllib and would make it easier to embed it in a larger Tcl application.