message: DOC: add RECURSIVE attribute to doxygen config
diff: PROJECT_NAME = Mint
  PROJECT_BRIEF = "Mint: Mesh Infrastructure Toolkit"
  -INPUT = @PROJECT_SOURCE_DIR@/src/mesh
  +INPUT = @PROJECT_SOURCE_DIR@/src
  +RECURSIVE = YES
  GENERATE_XML = YES
  USE_MATHJAX = YES
  FILE_PATTERNS += *.md *.markdown *.cpp *.hpp
  