Create top-level public/ header directory.

Create top-level public/ header directory.

These are the only files that embedders of PDFium should be including.
They are entirely self-contained, and compile cleanly against -Wall so
as to not offend the code that may include them.

Having done this, we can see that chromium is pulling in two additional
files from the fpdfsdk/include/pdfwindow directory, which is not guaranteed
to work.

A few files are renamed, adding an "_" to make the names consistent.
The exception is fpdfview, which is doc'd as such in the doc.

Naturally, paths will need updating in a handful of files in chrome
when this rolls in.

BUG=pdfium:154
R=thestig@chromium.org

Committed: https://pdfium.googlesource.com/pdfium/+/ac19d2d8f64ab87577f167e0a8df075a7fe3ffdc

[Tom Sepez, 2015-05-08 21:16:58]

tsepez@chromium.org changed reviewers:
+ jam@chromium.org, thestig@chromium.org

[Tom Sepez, 2015-05-08 21:16:59]

Lei, for review.  Let me know what you think about this proposal.

+jam@ for add'l wisdom.

[Lei Zhang, 2015-05-08 23:57:36]

Can we cleanup the whitespaces/tabs separately, so that git can figure out in
this CL that the files are being moved? i.e. all the public/ headers should be
of status "A+".

[jam, 2015-05-11 15:54:08]

On 2015/05/08 21:16:59, Tom Sepez wrote:
> Lei, for review.  Let me know what you think about this proposal.
> 
> +jam@ for add'l wisdom.

great idea, public >> fpdfsdk for anyone looking at this for the first time

[Tom Sepez, 2015-05-11 16:42:37]

On 2015/05/08 23:57:36, Lei Zhang wrote:
> Can we cleanup the whitespaces/tabs separately, so that git can figure out in
> this CL that the files are being moved? i.e. all the public/ headers should be
> of status "A+".

Good Point.  Done.

[Lei Zhang, 2015-05-11 21:22:27]

lgtm

[Tom Sepez, 2015-05-11 21:27:29]

Committed patchset #5 (id:80001) manually as
ac19d2d8f64ab87577f167e0a8df075a7fe3ffdc (presubmit successful).