Documentation: Minor fix for the PCA docs

This fixes some typos in the PCA documention.
Add contents title
Documentation: Change format for multiple modules

- Changed the documentation format for following modules:
    - Multilogistic Regression
    - Summary
    - Correlation
    - Cox Proportional Hazards
Documentation: Add note about table names and other corrections

- Updated description file to remove "Beta" statement
- Added a note about table and column names requiring double quoting
if name is case-sensitive or contains multibyte characters.
- Changed all the argument types to be succint.
- Made significant updates to the Linear System documentation to
correct many errors.
Abstraction layer: Change setp to this->setp

- Upgrading gcc to 4.7 leads to the following error:
../src/dbal/OutputStreamBufferBase_impl.hpp:75:9: error: 'setp' was
not declared in this scope, and no declarations were found by
argument-dependent lookup at the point of instantiation [-fpermissive]
../src/dbal/OutputStreamBufferBase_impl.hpp:75:9: note: use 'this->setp' instead

- Making that change fixes the problem
Doxygen: Update user and developer doxygen settings

Changes:
    - New tags were added for "Online Help" and "Output"
    - Collaboration and class graphs removed from user doc
    - External file lists removed from user doc
SVEC: Add out-of-bounds check even if size=0
Merge branch 'integration' into doc_kmeans
Merge branch 'integration' of https://github.com/madlib-internal/madlib into doc_kmeans