Code Cleanup

- Cmake was not updating HAVE_ST_BIRTHTIME.
- NIBBLER_FEATURE_DATE was not properly applied everywhere.
- FEATURE_COLOR was not properly set.
- Some source files failed to include cmake.h, and therefore were not properly
- Removed inefficient use of std::string::substr for guaranteed single character
  strings.
- Integrated Directory::cd.
- Integrated File::ctime, ::btime.
- Integrated Path::operator+.
- Integrated Nibbler::getDigit{2,4,6}.
- Integrated HighResTimer.
  enabling/disabling code.
- All Path objects now expanded internally to absolute form.
- Modified unit tests to accomodate absolute paths.
- Merged new nibbler.t.cpp tests.
- Made various methods const.
- Includes removed from some files, added to others.

src/Nibbler.h

@@ -28,6 +28,8 @@
 #ifndef INCLUDED_NIBBLER
 #define INCLUDED_NIBBLER
 
+#include <cmake.h>
+
 #define NIBBLER_FEATURE_DATE
 //#undef  NIBBLER_FEATURE_DATE
 
@@ -63,6 +65,9 @@ public:
   bool getN (const int, std::string&);
   bool getQuoted (char, std::string&, bool quote = false);
   bool getDigit (int&);
+  bool getDigit6 (int&);
+  bool getDigit4 (int&);
+  bool getDigit2 (int&);
   bool getInt (int&);
   bool getHex (int&);
   bool getUnsignedInt (int&);
@@ -76,8 +81,8 @@ public:
   bool getUUID (std::string&);
   bool getPartialUUID (std::string&);
   bool getDateISO (time_t&);
-#ifdef NIBBLER_FEATURE_DATE
   bool parseDigits(std::string::size_type&, int&, unsigned int, bool strict = true);
+#ifdef NIBBLER_FEATURE_DATE
   bool getDate (const std::string&, time_t&);
 #endif
   bool getOneOf (const std::vector <std::string>&, std::string&);