tools: Correct usage script names in README
tools: Add empty sloccount.sh script

Issue #53.
tools/sloccount: Add get_project_root() function

Issue #53.
tools/sloccount: Add find_files_with_extension()

Issue #53.
tools/sloccount: Add print_sloccount_for_files()

Issue #53.
tools/sloccount: Sort results of find_files_with_extension()

Issue #53.
tools/sloccount: Complete implementation

Issue #53.