Conforming names fixed

Fixed include guards to be standards conforming.

The C++ Standard [ISO/IEC 14882-2003], Section 17.4.3.1.2
add header file for std::min (<algorithm>)
Merge pull request #6 from wendazhou/std_min_header_fix

add header file for std::min (<algorithm>)
Can run a single group from the cmd line.

Using the "-g" command line option, a single benchmark group can now be
specified to run from the command line to bypass running all benchmarks
contained in a single Celero executable.
Moved Demos into their own projects.

While each demo was moved into its own project, there is no reason that
all of the demos could not have been compiled together into a single
Celero executable.  They were broken out to aid in learning how to use
Celero.
Modified baseline calculation.

The previous baseline calculation did not consider the number of
iterations used within a single test.  All demos used the same number by
comparison, so this bug did not show up.  Now, the baseline comparison
assumes that the body of each benchmark or baseline function body has
equal weight within a specific benchmark case.  This seems more
intuitive and should provide more accurate baseline results.