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.


[ROCm/hip commit: eced013ae4]

projects/hip/docs/RuntimeAPI/html/search/classes_5.js

@@ -1,7 +1,5 @@
 var searchData=
 [
-  ['long1',['long1',['../structlong1.html',1,'']]],
-  ['longlong1',['longlong1',['../structlonglong1.html',1,'']]],
-  ['longlong3',['longlong3',['../structlonglong3.html',1,'']]],
-  ['longlong4',['longlong4',['../structlonglong4.html',1,'']]]
+  ['texture',['texture',['../structtexture.html',1,'']]],
+  ['texturereference',['textureReference',['../structtextureReference.html',1,'']]]
 ];