Revert "Update build scripts for Sencha. We need an additional symbols.js target to list Sencha Cmd compiler directives for VexFlow classes. Compression of the javascript is also disabled, for ease of debugging (plus, Sencha Cmd will automatically add compression when the library is included in a Sencha project)."

This reverts commit 8a760229a7f8bc176e8998b52dbc3e2d89ac7dd1.
Revert "Add return value to SConstruct."

This reverts commit 77fccd26a45dc17b5026ee291a42615278068d19.
Revert "Update build scripts for Sencha. We need an additional symbols.js target to list Sencha Cmd compiler directives for VexFlow classes. Compression of the javascript is also disabled, for ease of debugging (plus, Sencha Cmd will automatically add compression when the library is included in a Sencha project)."

This reverts commit 8a760229a7f8bc176e8998b52dbc3e2d89ac7dd1.