Doc: Add glossary, fix type API reference page.
TS-2158: Properly mark an IP as non-routable for IPv4 and IPv6 link local
addresses as well as IPv6 private addresses and IPv4 Carrier Grade NAT
addresses from RFC 6598.
doc: fix logbuild links
TS-1424: Change EREMOTEIO to ECONNABORTED
ci: flip the 3.4.x branch to 4.0.x
ci: make git scm polling less aggresive
TS-2154: Lua plugin asserts traffic_server on startup

The Lua plugin keep a number of per-instance hook tables. TS-1469
added a hook, but the Lua plugin was never updated, so we ended
passing a NULL continuation pointer to TSContDataSet() in
LuaPluginInstance::init(). Lets add the missing hook, and also add
a static assertion so that the next person do add a hook knows that
this requirement exists.
TS-2160: Add ats_is_ip_private and ats_is_ip_linklocal functions.
TS-2160: Remove use of ats_is_ip_nonroutable and replace with
ats_is_ip_linklocal and ats_is_ip_private.
TS-2160: Remove ats_is_ip_nonroutable.
TS-2160: Update CHANGES.
doc: move cache glossary into the main glossary
TS-2156: Fix stats trap in different type of threads

There are two ways to create threads in ATS:
1) By EventProcessor::spawn_event_threads(), such as ET_NET threads.
2) By EventProcessor::spawn_thread(), such as flush thread.

But I found that we can't stats the same things across these two type of
threads.

This patch will make stats in both type of threads transparent for upper
layer developers.

BTW: renames "dthreads" to "all_dthreads" to keep naming consistency with
     "all_ethreads".

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
TS-2161: TSHttpTxnHookAdd memory Leak

Make sure that the FeatureAPIHooks destructor correctly frees the
APIHook list.
Some indentation and printf cleanup
TS-2162: Auto-created collation LogObject would be misused by access log

When collation host receives LogBuffer data from network, it'll create
LogObject according the data's format automatically.

Since the LogFilter of these auto-created LogObjects are empty, they
will be misused by access log generated by collation host itself –
toss_this_entry() will always return false when m_does_conjunction is
set.

This patch introduces a new member variable: m_auto_created in LogObject,
so that we can distinguish this type of LogObject to avoid misusing.

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>
TS-2145: Add metrics for log collation

Without accurate stats, we don't known whether the log is lost.
This patch is used to verify, such as:

1) At log client side, how many logs genterated from HttpSM, how many
   logs sent to LogServer.

2) At log server side, how many logs received from LogClient, how many
   logs written to LogServers's disk.

Signed-off-by: Yunkai Zhang <qiushu.zyk@taobao.com>