Add simple dialog to set TWISS args
Merge pull request #25 from coldfix/twiss-dialog

Add dialog to define initial conditions for twiss
Add generic input dialog base classes
Use utility base class for ModelDetailDlg
Use utility base class for OpenModelDlg
Add simple BeamDialog [preliminary]

Limitations:

- can not yet be used to set values, since cpymad.Madx does not
  implement this at a convenient level
- is too large by default (shows almost all values)
Fix name parameter for Model in plainopen

The name parameter should always be the name of a sequence as it is used
that way inside the Model code.
Add sequence choice when opening .madx files
Make separate MadxUnits component

The responsibility of this component is to remove and units to push them
to MAD-X.

For now the Model just inherits from that class to retain backward
compatibility.
Add basic unit support to BeamDlg and TwissDlg
Merge branch 'improve-dialogs'
Use menu items for BEAM/TWISS dialogs
Add a status bar to the frame

The status bar can be used to display helpful messages (like menubar
help strings).
Merge pull request #32 from coldfix/toolbar2menu

Replace TwissDialog toolbar tool with menuitem
Remove TwissDialog.menuitem.UpdateUI handling

The UpdateUI handling for notebook.menubar is sufficient.
Merge branch 'follow-up-fix'
Create Madx instance with every new frame

There is a subtle but major bug in this change:

NotebookFrame.Reserve creates new frames with models that are based on
the Madx instance of the initiating frame.
Add method NotebookFrame.Claim

The method is used to transfer ownership of the frame to a specific
model/file. This fixes the bug mentioned in the previous commit message.
Set help messages for 'Open' menu items  dynamically
Merge pull request #37 from coldfix/frame-equals-madx

Immediately start a Madx instance for every new Frame