- documentation fixes
- improvements to geotiler-lint script
  - there is no need for BadComposure exception anymore
  - program description readded to the argument parser
- project status moved as a section into introduction chapter of the
  documentation
- documentation updates
- removed geotiler.tiles module and moved its content to appropriate
  provider modules
  - the from/to functions reimplemented to fit Python 3 better (i.e. no need
    for from/toBinary functions anymore)
  - goetiler.tiles doctests moved to appropriate unit tests modules