message: Use markdown for main page. Fix some doxyfile
diff: @@ -208,7 +208,7 @@ SEPARATE_MEMBER_PAGES = NO
  # uses this value to replace tabs by spaces in code fragments.
  # Minimum value: 1, maximum value: 16, default value: 4.
  -TAB_SIZE = 4
  +TAB_SIZE = 2
  # This tag can be used to specify a number of aliases that act as commands in
  # the documentation. An alias has the form:
  @@ -889,7 +889,7 @@ FILTER_SOURCE_PATTERNS =
  # (index.html). This can be useful if you have a project on for instance GitHub
  # and want to reuse the introduction page also for the doxygen output.
  -USE_MDFILE_AS_MAINPAGE =
  +USE_MDFILE_AS_MAINPAGE = doc/common/main_page.md
  #---------------------------------------------------------------------------
  # Configuration options related to source browsing
  @@ -1147,7 +1147,7 @@ HTML_DYNAMIC_SECTIONS = NO
  # Minimum value: 0, maximum value: 9999, default value: 100.
  # This tag requires that the tag GENERATE_HTML is set to YES.
  -HTML_INDEX_NUM_ENTRIES = 100
  +HTML_INDEX_NUM_ENTRIES = 2
  # If the GENERATE_DOCSET tag is set to YES, additional index files will be
  # generated that can be used as input for Apple's Xcode 3 integrated development
  