Update changelog for 1.0 release

CHANGES.txt

@@ -1,3 +1,46 @@
+1.0.0
+~~~~~
+
+Folium has been stable for a couple of years now. We hardly have breaking changes and the feature
+set is stable. We don't expect the scope of what Folium is and isn't to change significantly. 
+So it's time for a 1.0 release.
+
+Breaking changes
+
+- Use write_png from Branca, remove from Folium (@Conengmo #1708)
+- Remove deprecated Map.choropleth method (@Conengmo #1684)
+
+New features
+
+- Draggable layer control option (@Conengmo #1760)
+- Add fit enabled overlays feature (@Conengmo #1693)
+- Add type hints (@Conengmo #1677)
+
+Improvements
+
+- Allow Choropleth key_on to traverse through array (@amrutharajashekar #1772)
+- Support TagFilterButton in PolyLine, AntPath and GeoJson (@jamiechoi1995 #1756)
+- Multiple instances of TimeSliderChoropleth on a single map (@Conengmo #1749)
+- Make VectorGridProtobuf an overlay by default (@iwpnd #1723) 
+- Change internally where layers are added to the map (@Conengmo #1690)
+- TimestampedWmsTileLayers inherit from MacroElement, not Layer (@Conengmo #1696)
+- SideBySideLayers inherit from MacroElement, not Layer (@Conengmo #1695)
+- Consolidate duplicate utility functions with Branca (@Conengmo #1676)
+
+Bug fixes
+
+- Fix interaction between DualMap and Draw (@Qweaper #1776)
+- Fix MeasureControl plugin for Leaflet>=1.8.0 (@Conengmo #1748)
+- Pin older version of leaflet side by side to fix SideBySideLayers plugin (@jtmiclat #1732)
+- Fix Map.show_in_browser() by adding local file prefix to url (@RileyLeff #1704)
+
+Documentation
+
+- Deprecate example notebooks (@Conengmo #1798)
+- Documentation overhaul (@Conengmo #1700)
+- Update example notebooks after new Pandas version (@Conengmo #1761)
+
+
 0.14.0
 ~~~~~~