Tiger 2017 data support

[robe]

The census usually releases tiger data in mid-August.

They are a tad late, however I see they have created the 2017 folder

​https://www2.census.gov/geo/tiger/TIGER2017/

Which means they probably aren't too far off from releasing.

I suspect they will release the data just in time for us to include the load scripts as part of PostGIS 2.4.0

[robe]

I'll push this to 2.5 and push back to 2.4 if Tiger comes out before release.

[robe]

Yeh they finally came out with tiger 2017 data and looks like they went back to just regular old ftp. ​ftp://ftp2.census.gov/geo/tiger/TIGER2017/

I'm going to push this to 2.4.1 and hopefully I won't have to make too many changes.

[robe]

Looks like they significantly changed the edges structure enough to make it dangerous to backport as I'll probably need to make structural changes or rethink load script.

At a glance looks like they decided to alphabetize the columns in edges. Not sure why they didn't bother doing that with the other tables.

[robe]

In 15984:

Fix tiger 2017 edges load issue by doing following:

insert to be ordered by column name instead of ordinal_position.

Exclude divroad from edges load which now appears to be no longer present in 2017 edges data.

References #3815 for trunk PostGIS 2.5.0

[robe]

In 15985:

Fix tiger 2017 zcta5 load logic, but leave default as turned off (takes 30 minutes to process)

References #3815 for trunk PostGIS 2.5.0

[robe]

Was able to get to work without any structural changes so will back-port

[robe]

In 15986:

Update docs to reflect zcta5 fix and also upgrade to tiger 2017 load

References #3815 for trunk PostGIS 2.5.0

[robe]

In 15987:

Tiger 2017 and zcta load support for PostGIS 2.4.1
Closes #3815

[robe]

In 15989:

flag zcta5 addition as an enhancement not a change. References #3815

[robe]

In 15991:

Backport geography changes to PostGIS 2.4.1
Closes #3902
Changed Changed to Enhanced for tiger zcta
References #3815 for PostGIS 2.4.1