Tutorials objects (#5)

* tutorials: add objects tutorial

* Tutorials: localize object illustration

* Tutorial: objects -- revisions

Minor typos / edits, put asides in blockquotes, clarify S3 as only available class model

* spacing

* Embed examples in setup() so Processing.R can run the code as they go; change print statements to built-in

* Final code: move main program code to top

by convention globals-settings-setup go first in Processing sketches

* Final code: revise comment headings

* Add note on no tab support in Processing.R

Plus minor line edits for clarity

* Place example ball inside 100x100 viewport

so that test sketches can see it by default event before specifying a settings(){ size(x,y) }

* Final sketch: add simple looper

so that contents remain visible even without bounce code

* Typo in image link

* objects: Add

Signed-off-by: Ce Gao <ce.gao@outlook.com>

Author: gaocegege

tutorials/index.yml

@@ -1,3 +1,4 @@
 index:
   - gettingstarted
   - drawing
+  - objects

tutorials/objects/.property.yml

@@ -0,0 +1,5 @@
+image: objects.jpg
+title: Objects in Processing.R
+author: Shawn T. O'Neil
+introduction: The basics of object-oriented programming.
+level: Intermediate