POI dict and polyline support

Added support for filter functions to return dicts.
Added support for filter functions to return a list of coordinates to
draw lines between when shown.
Merge branch 'master' into POI-Polylines
Add section about importing in the config file

Add a section that describes how users can import parts of their config from other files.
nbt timestamps are probably signed (like time_t)

Besides, we get overflow errors with utime on windows for large
unsigned 32-bit integers.
Docs updates for #882 (JSObserver formatting strings)
Added: Hay blocks, Hardened Clay, Coal blocks, and Carpet.
Added stained hardened clay
Add all stem and all cap blocks for big mushrooms.
added support for hashchange event for recent browsers
hashchange triggered by setHash is now properly ignored
Changed default poititle to "Markers"

I feel this is more accurate and it has been bugging me for a
while now.
Added option showlocationmarker
removed bit about __init__.py
Merge branches 'config-include', 'hashchange', 'poi-polylines', 'showlocationmarker' and 'signed-timestamps'
updated contributors list
Use protocol-relative scripts in index.html
Update signs.rst

Add warning about non-existent icon files
Fix reference to stochastic command line option
Revert "Use protocol-relative scripts in index.html"

This reverts commit fabc244c916815c17ca3fcd76dcd75084ff43dde.
Using protocol-relative scripts broken users who don't use webservers
(i.e. file:/// )
Merge pull request #937 from tswsl1989/patch-2

Fix reference to stochastic render command line option