Add skeleton for application.

lib/docs/Cache_Lite/Cache/docs/technical

+Technical choices for Cache_Lite...
+-----------------------------------
+
+To begin, the main goals of Cache_Lite :
+- performances
+- safe use (even on very high traffic or with NFS (file locking doesn't work
+            with NFS))
+- flexibility (can be used by the end user or as a part of a larger script)
+
+
+For speed reasons, it has been decided to focus on the file container (the 
+faster one). So, cache is only stored in files. The class is optimized for that. 
+If you want to use a different cache container, have a look to PEAR/Cache.
+
+For speed reasons too, the class 'Cache_Lite' has do be independant (so no 
+'require_once' at all in 'Cache_Lite.php'). But, a conditional include_once
+is allowed. For example, when an error is detected, the class include dynamicaly
+the PEAR base class 'PEAR.php' to be able to use PEAR::raiseError(). But, in
+most cases, PEAR.php isn't included.
+
+For the second goal (safe use), there is three (optional) mecanisms :
+- File Locking : seems to work fine (but not with distributed file system
+                 like NFS...)
+- WriteControl : the cache is read and compared just after being stored
+                 (efficient but not perfect)
+- ReadControl : a control key (crc32(), md5() ou strlen()) is embeded is the 
+                cache file and compared just after reading (the most efficient
+                but the slowest)