curl_easy_setopt: Fixed OAuth 2.0 Bearer option name

Bug: http://curl.haxx.se/bug/view.cgi?id=1313
Reported-by: Viktor Szakáts
pop3: Moved APOP detection into pop3_state_servergreet_resp()

In an effort to reduce what pop3_endofresp() does and bring the POP3
source back inline with the IMAP and SMTP protocols, moved the APOP
detection into pop3_state_servergreet_resp().
pop3: Moved CAPA response handling to pop3_state_capa_resp()

Similar to the processing of untagged CAPABILITY responses in IMAP and
multi-line EHLO responses in SMTP, moved the processing of multi-line
CAPA responses to pop3_state_capa_resp().
pop3: Fixed processing of more than one response when sent in same packet

Added a loop to pop3_statemach_act() in which Curl_pp_readresp() is
called until the cache is drained. Without this multiple responses
received in a single packet could result in a hang or delay.
pop3: Fixed selection of APOP when server replies with an invalid timestamp

Although highlighted by a bug in commit 1cfb436a2f1795, APOP
authentication could be chosen if the server was to reply with an empty
or missing timestamp in the server greeting and APOP was given in the
capability list by the server.
vtls: created subdir, moved sslgen.[ch] there, updated all include lines
vtls: moved all TLS/SSL source and header files into subdir
openssl: renamed backend files to openssl.[ch]
vtls: renamed sslgen.[ch] to vtls.[ch]
Makefile.inc: specify the vtls sources+headers separately
Makefile.inc: use standard source header
pop3: Fixed APOP timestamp detection from commit 1cfb436a2f1795
RELEASE-NOTES: Synced with 812c5ace759d04
pop3: Added debug information to assist with test864 failure
Revert "pop3: Added debug information to assist with test864 failure"

This reverts commit 727d798d680f29c8b3cb7d7f03d6b6a3eb4356da.
Curl_pp_readresp: zero terminate line

The comment in the code mentions the zero terminating after having
copied data, but it mistakingly zero terminated the source data and not
the destination! This caused the test 864 problem discussed on the list:

http://curl.haxx.se/mail/lib-2013-12/0113.html
Signed-off-by: Daniel Stenberg <daniel@haxx.se>
Curl_pp_readresp: replace stupid loop with memcpy
email: Extended the login options to support multiple auth mechanisms
code police: fix indent level to silence checksrc complaints
email: Fixed segfault introduced in commit 195b63f99c2fe3