Fix many doc L<> errors

Fix many doc L<> errors

Add 2017 copyright year
Add missing typedef to NAME
Remove ec(7) and bn(7) doc links
Remove .pod link errors, bogus links, make a few typo corrections
Fix some typo's in links and some missing items.
Don't link to C runtime functions (See OPENSSL_malloc for example/precedent)
Document ASN1_tag2str(), add a few typedef's that were missing from NAME
Update doc-nits target; addresses
    https://github.com/openssl/openssl/pull/1900#issuecomment-259943891,
Merge check-doc-links into find-doc-nits; if run regularly, would have found
    https://github.com/openssl/openssl/pull/2825

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2862)
(cherry picked from commit 9e183d2271653cbba2d9cf56d40c1356705207aa)