trim trailing spaces
fix documentation typos & style

typo corrections:
 - otherwisee --> otherwise
 - it's is --> it is
 - nuber --> number
 - will likely to use --> is likely to use
 - varaible --> variable
 - defauled --> defaulted

stylistic changes:
 - which would make --> making
escape first dash ('-') in double-dashes ('--') found in doxygen comments

This should prevent doxygen from generating bad documentation HTML pages
containing '<ndash></ndash>' where those double-dashes should be.
Merge pull request #6 from jurko-gospodnetic/develop

Documentation cleanups from  Jurko Gospodnetić:

- trim trailing spaces
- fix documentation typos & style
- escape first dash ('-') in double-dashes ('--') in doxygen comments
This should prevent doxygen from generating bad documentation HTML pages
containing '<ndash></ndash>' where those double-dashes should be.