Copy main.cpp to "deprecated" folder

This file (originally main.cpp) was written when TBD's primary aim was to
evolve into a unit/regression test suite.  However, recent changes in
focus have shifted project goals towards those of a code-base analysis
CLI tool.

This main file then, written as a shell to show CLI syntax for the
proposed unit test suite, has no real place in the project as it
is currently geared.  However, it is a useful document to maintain
in case focus shifts in the future, or a fork of this project wishes
to take on a similar goal.
Modify main.cpp for C++ style

In poor practice, this commit introduces two changes to main.cpp

First, the list of accepted execution modes for the TBD CLI tool
has been changed from those befitting the unit testing tool to those
befitting a code-base analysis tool.  (i.e. styletest, writetest,
runtest etc. are removed, and 'stats' was added).

Second, the command line arguments were previously being handled as
an array of char*'s.  Though this got the job done initially, it
is poor C++ practice to mix char *'s with the use of std::string.
To maintain consistency with the remainder of the project, the arguments
were converted to std::string immediately upon entering the main method.
Remove declaration for handleRemainingArguments()

The function handleRemainingArguments() had been removed in a previous
commit, however the header declaring it for the compiler had not been
removed.  In previous revisions the function was responsible for setting
a series of static char * variables, without knowing the mode.

In retrospect, it was deemed a better idea for each mode of operation
to handle its own arguments, rather than having a central monolithic
function for argument handling.