Fix broken hosted-paper link and typos in topic READMEs (#894)

* Fix broken hosted-paper link and typos in topic READMEs

The FRP index links the hosted paper as
[Deprecating the Observer Pattern](deprecating-the observer-pattern.pdf).
The file on disk really is named with a space, but an unescaped space is not
allowed in a CommonMark link destination, so the entry renders as literal text
instead of a link. Percent-encode the space so it resolves to the committed PDF.

Also correct misspellings in paper titles and descriptions:

- Algorithims -> Algorithms (comp_sci_fundamentals_and_history)
- simplifed -> simplified (data_structures)
- sucessful -> successful, numberator -> numerator,
  demoninator -> denominator, authoratitative -> authoritative
  (information_retrieval)
- Expresions -> Expressions (logic_and_programming)
- represention -> representation (mathematics)
- Probablistic -> Probabilistic (robotics, sublinear_algorithms)
- Philppe -> Philippe (streaming_algorithms)

* Rename the Deprecating the Observer Pattern PDF to drop the space

Per review, renaming the file rather than percent-encoding the link.

robotics/README.md

@@ -9,7 +9,7 @@ Robotics
 
 [Online Trajectory Generation: Basic Concepts for Instantaneous Reactions to Unforeseen Events](http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=5350749)
 
-[Probablistic Roadmaps for Path Planning in High-Dimensional Configuration Spaces](https://www.cs.cmu.edu/~./motionplanning/papers/sbp_papers/PRM/prmbasic_01.pdf)
+[Probabilistic Roadmaps for Path Planning in High-Dimensional Configuration Spaces](https://www.cs.cmu.edu/~./motionplanning/papers/sbp_papers/PRM/prmbasic_01.pdf)
 
 [Rapidly-Exploring Random Trees: A New Tool for Path Planning](http://msl.cs.uiuc.edu/~lavalle/papers/Lav98c.pdf)