- drop python 3.4 support
- remove the "by delta" checkbox in orbit correction dialogs, always use the
  measured monitor position if possible
- depend on cpymad 1.1.0
- auto-update plotted monitor markers
- fix Ctrl+P closing mainwindow
- handle menu hotkeys within all application windows
- add menu options and hotkeys to increase or decrease font size
- remember font size setting
- some bugfixes
- remove obsolute "Update" buttons from diagnostic dialogs

internal:

- move ORM analysis code its own independent package
- add PyQt5 as regular dependency (can automatically installed via pip)
- add tests on py35
- refactor modules in ``madgui.plot``
- remove context-managing ability from ``Session``
- replace ``pyqtSignal`` by our own lightweight solution (in preparation for
  letting models etc be instanciated without GUI)
- not subclassing ``cpymad.madx.Madx`` anymore, moved functionality directly
  to cpymad
- refactor/simplify caching classes
- make ``twissfigure`` module more independent from mainwindow/session and
  simplify plotting API (standalone functions that can be used without madgui)
- refactor scene graphs, prepare for fully consistent management of all scene
  elements via curvemanager dialog
- optimize performance when updating plot
- fix error while building the documentation
- start a developer's guide documentation section
- introduce a lightweight history type to manage history in several components
- use PyQt5 imports directly, remove the ``madgui.qt`` compatibilty module
- split up the correction dialogs into components, in preparation for a great
  unification