examples/upload-file: Missing semicolon.
Add new examples "link" and "direct-link".
ReadMe: Update "Create app" docs to reflect new flow on Dropbox website.
Bail out if 'mbstring.func_overload' is set.

This option changes the behavior of the standard PHP string functions,
which breaks our code.
examples: Good error message if script isn't run as a CLI app.

Some people were trying to use these examples as server-side PHP
pages, which doesn't work, and yields a hard-to-understand error
message.
examples: Use "===" and "!==" instead of "==" and "!=".
examples: Get web-file-browser.php to work with an existing web server setup.

Should now work with an Apache/mod_php-style web server setup, as well
as with "php -S".
Move "test/strict.php" "lib/Dropbox/strict.php" so others can use it.

Was using it in example code.  Decided it was bad for the examples to
have a dependency on the "test" folder.
Client: Example code in docs forgot to close file handle.
examples: web-file-browser: Minor tweaks.

- Change "==" to "==="
- Tweak comment and error message.
examples/web-file-browser: Fix "download file" feature for non-built-in-server cases.

Link to download file assumed app was at "/".  Call getPath() to get
the actual root path.

Also:
- Moved download feature to "/download" instead of having it be a
  parameter on "/"
- Moved "/upload" handler up to be near "/" and "/download".
examples/web-file-browser: Better error handling (filled in HTTP code TODOs; exception instead of error_log for fatal errors).
WebAuth: Don't assert() on bad CSRF token from session.

Let the app deal with it like any other CSRF mismatch.
examples/web-file-browser: Add comment about why it's an assert() and not something weaker.
examples/web-file-browser: Don't need to 'unset' (WebAuth.finish() does that for us).
Client: Fix bug in chunked uploader.

If a chunk gets uploaded but the response gets lost, we try again.
Upon retry, the server tells us our offset is at the end of the chunk.
Instead of considering the chunk done at that point, we were trying
to upload a zero-length substr() at the end of the chunk.

PHP's substr() considers it an error to try and do that.

Thanks to Brian Reavis for reporting.
Stricter validation of $accessToken and $clientIdentifier.

These values are put in HTTP headers without escaping, which can cause
weird bugs.  For example, a newline will cause the stuff after the
newline to be interpreted as a new HTTP header.
Add support for "path_prefix" parameter to /delta.