update TODO with all the subtasks for internal linking and new tests needed
[ADD] proper internal linking for file://_site/ URLs, including check for navigationType, url building in webViewShouldStartLoadWithRequest. needs cleaning up.
clean up comments/indents for internal link code
[REMOVE] needless URL rebuilding
[DONTNEED] old commented-out code. sigh of relief.
improve VC setup so that both internal link and initial loads run the same directory availability check, minimize repeated code
[DONTNEED] commented-out code from previous, messier setUpPage method
make correctDirectory method more reusable so we can get rid of self.baseDirectoryToUse and fetchUpdate checks correct version.txt