Big refactoring of C code:

* Splits big ruby_prof.c file into a bunch of subfiles based on class
* Removes 1.9.1 support
Updated vc project file.
Update dates in copyright in license
VC project ignores.
Clean up superclass check by moving to its own method and removing nested #ifdefs
Only support 1.8.7, 1.9.2 and higher. Remove check for ruby methods that no longer exist in Ruby 1.9.3
Remove remaining 1.9.1 code.
Big commit that separates out all the measurement classes to their own c files and adds a measure_t struct type that can be passed around allowing multiple methods to be defined in it (measure, convert, start/stop at some point).
Get rid of convert functions - they only apply to cpu time and memory and can just be included in the measure call.
Get rid of rdoc that has moved to real ruby measurement classes.
Create a RubyProf::Profile class and clean up duplicated methods.
Updated VC project.
Remove old result object, this is now part of the main profile class.
Rename rp_method_info to rp_method
Clean up measure modes a bit.
Move switch_thread to thread files.
Minor formatting change.
New profile and measure files.
No more result object....
Add compatibility file to support old api.