ReST directive was used. Also fixed some other ReST directives that were
not correct and removed some warnings during buildbot checks.

- Used lunix style slashes - works on most systems
- Removed all trailing whitespaces

All errors were found by doc/check_docs2.py

Some reST syntax correction. Now the PDF documentation builds correctly under Windows using MIKTEX. Some update on the tutorial structure. Some CSS syntax correction. Windows Install Tutorial v0.4. 

a lot of small corrections to bring down the number of undocumented functions, reported by the script; added em.cpp sample

started work on API & doc synchronization (in particular, Mat& => Input/OutputArray in the descriptions)