[Doc] Add installation instructions for Ubuntu PPA

Cherry-pick of trunk r3164.

Fix version displayed by Doxygen docs

Bump version to 2.1.0

Bump version for 2.0.2 maintenance release

Bump version for 2.0.1 maintenance release

On Unix-like systems, $python_prefix defaults to $prefix

added pfr example

copy cti files to Python flame demo directory

modified csvdiff to allow larger error bounds when solution is changi…

…ng rapidly

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