Unit tests for mnp::string::count() and mnp::string::find().
Reorganized file and class structure.
Renamed basic_string_impl class to string_funcs and moved it into its own header files.
Merge branch 'file_reorganization' into anil-test-cases

Conflicts:
	my_string.h
	str_manip.xcodeproj/project.pbxproj
Fixed missing files in the project config after merge.
substr implemented, count/find bugs fixed. removed user-specific files from the xcodeproj package.
removed user specific files from xcodeproj package.
updated gitignore.
Combined count unit test implemented.
Merge pull request #3 from anilanar/migration-to-immutable-string

migration to immutable, ref-style string