- get the doc of the enums in MatrixBase right

- get the doc of the flags in Constants right
- finally give up with SEPARATE_MEMBER_PAGES: it triggers too big
  Doxygen bugs, and produces too many small pages. So we have one
  huge page for MatrixBase at currently 300kb and going up, so the
  solution especially for users with low bandwidth will be to provide
  an archive of the html documentation.

doc/Doxyfile.in

@@ -182,7 +182,7 @@ INHERIT_DOCS           = YES
 # a new page for each member. If set to NO, the documentation of a member will 
 # be part of the file/class/namespace that contains it.
 
-SEPARATE_MEMBER_PAGES  = YES
+SEPARATE_MEMBER_PAGES  = NO
 
 # The TAB_SIZE tag can be used to set the number of spaces in a tab. 
 # Doxygen uses this value to replace tabs by spaces in code fragments.
@@ -1177,7 +1177,8 @@ INCLUDE_FILE_PATTERNS  =
 # instead of the = operator.
 
 PREDEFINED             = EIGEN_EMPTY_STRUCT \
-                         EIGEN_PARSED_BY_DOXYGEN
+                         EIGEN_PARSED_BY_DOXYGEN \
+                         EIGEN_VECTORIZE
 
 # If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then 
 # this tag can be used to specify a list of macro names that should be expanded.