Update docs:

- Some comments in hip_hcc.cpp
 - document hipHostRegister* flags.
 - expand docs on hipHostRegister/Unregister. Use "register" rather than
   "pin" to describe action these take.
 - change required CUDA version to 6 (require unified memory)
 - remake doxygen.

docs/RuntimeAPI/html/search/search.js

@@ -7,11 +7,11 @@
 
 var indexSectionsWithContent =
 {
-  0: "_abcdeghilmnoprstwxyz",
-  1: "dhit",
+  0: "_abcdefghilmnoprstwxyz",
+  1: "dfhist",
   2: "h",
-  3: "h",
-  4: "achlmnprstwxyz",
+  3: "gh",
+  4: "achilmnprstwxyz",
   5: "dh",
   6: "h",
   7: "h",