Deleted obsolete build script apply_exports_hack.py.

This script was a hack used to make the JavaScript code
work on both Node.js and in browsers. Now we build separate
versions of the code for both environments, so we no longer
need this script.

generate/apply_exports_hack.py

@@ -1,25 +0,0 @@
-#!/usr/bin/env python3
-import sys
-
-if __name__ == '__main__':
-    if len(sys.argv) != 2:
-        print('USAGE: apply_exports_hack.py js_filename')
-        sys.exit(1)
-    filename = sys.argv[1]
-    with open(filename, 'rt') as infile:
-        text = infile.read()
-
-    find = "})(this.Astronomy = {});"
-    repl = "})(typeof exports==='undefined' ? (this.Astronomy={}) : exports);"
-
-    if text.find(find) < 0:
-        print('ERROR: could not find target text in file: {}'.format(filename))
-        sys.exit(1)
-
-    text = text.replace(find, repl)
-
-    with open(filename, 'wt') as outfile:
-        outfile.write(text)
-
-    print('apply_exports_hack.py: patched file {}'.format(filename))
-    sys.exit(0)