Ctypes version ctypes1.py

ctypes1.py basically calls C version turned into library.
Modified algorithm to O(N*D)

challenge6?.py and challenge5.c uses an array of offset value to the next lower non-zero value in p_hist[].
This auxiliary data makes looping for the smaller price unnecessary.
challenge3.cpp too slow, half-modified (unfinished).
Working c++ prog (challenge3.cpp)

Need more optimization in input code.
C++ completed (challenge4.cpp).

Challenge4.cpp scored 0.01sec for all 3 test cases.
C version completed (rewrite of challenge4.cpp in C)
Bug fix and clean up for C/C++.

challenge4.cpp and challenge6.cpp are finalized for now.
Correct max_days from 75 to 300 (C/C++ limit).
Cleanup and some benchmarking code.

Added run-time duration adjuster (didn't work well on the Paiza environment).
Add more timer to challenge9b.py
Challenge13b.py: based on challenge9b.py, but self-implemented bisects
Challenge13b.py cleanup
Not using sys.stdin in challenge13/13b.py
Modify challenge13b.py

challenge13b.py:
not sorting cprices.
using list comprehension to make cprices list.
making cprices tuple instead of list.
not recording best prices, but immediately printing them.
Modify challenge13.py to match along with challenge13b.py
challenge13b.py and challenge13.py: Restored stdin
Modify challenge13b.py

use stdin.read().splitlines() for input
delete cp_sorted
Challenge13b.py temporary commit
Merge branch 'kuro'

Conflicts:
	challenge13b.py; simple blank line removal resolved it.
Remove some auto-backup files.
Challenge13b.py remove commented out lines, correct header comment