add projects sevensegment, sevensegment_test and pocketcalculator
include only header file
include only header file instead of whole source, and use dylib instead
remove 'Release' run configuration
include only header file instead of whole source, and use dylib instead
remove 'Release' run configuration
include only header file instead of whole source, and use dylib instead
don't export constant using 'static'

See explanation here (third use of the static keyword):
http://www.cprogramming.com/tutorial/statickeyword.html
remove debugging line