Add support for IPython Jupyter QT Console as a debugging aid

[kakaroto]

If manuskript is launched with its last argument set to "--console" an
interactive console opens up to help debug the application.
The IPython, qtconsole and matplotlib libraries must be installed for it
to work and they won't get imported unless the argument is passed to the app.

This is such an amazing tool, and it was quite a headache to get it to work, but now I can interactively debug things while the application is open and explore the outlineModel and items and the data and figure out how everything fits together.

Example of my current console log with all my trial/errors removed (I was trying to understand the outlineModelItem data, and how I can find children/siblings of items, and how to access the data in them) to showcase how useful it can be :

In[10]: root = MW.mdlOutline.rootItem

In[30]: root.childItems[1].data(0)
Out[30]: 'Prologue'

In[31]: prologue = root.childItems[1]

In[40]: str(prologue)
Out[40]: '<manuskript.models.outlineItem.outlineItem object at 0x00000267D59CB9E8>'

*** write a __str__ function then instead of restarting manuskript, I just dynamically modify the object in the console ***

In[47]: def __str__(self):
    return "{id}: {folder}{title}{children}".format(
        id=self.ID(),
        folder="*" if self.isFolder() else "",
        title=self.data(self.enum.title),
        children="" if self.isText() else "({})".format(self.childCount())
        )
        

In[48]: outlineItem.__str__ =__str__

In[51]: str(prologue)
Out[51]: '272: *Prologue(5)'

In[52]: root.children()
Out[52]: 
[<manuskript.models.outlineItem.outlineItem at 0x267d59b7630>,
 <manuskript.models.outlineItem.outlineItem at 0x267d59cb9e8>,
 <manuskript.models.outlineItem.outlineItem at 0x267d59cbd68>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a5ce10>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a5c048>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a66f28>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a66f98>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a90e10>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a90ef0>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a90f98>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a905f8>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a90c18>,
 <manuskript.models.outlineItem.outlineItem at 0x267d5a92320>]


In[54]: outlineItem.__repr__ =__str__

In[55]: root.children()
Out[55]: 
[277: Cover Page,
 272: *Prologue(5),
 271: *Part 1(15),
 292: *Interludes(2),
 295: *Part 2(6),
 293: *Interludes(0),
 294: *Part 3(25),
 316: *Interludes(0),
 318: *Part 4(0),
 317: *Interludes(0),
 319: *Part 5(0),
 320: *Epilogue(0)]

In[57]: part1 = root.children()[2]

In[58]: part1.parent()
Out[58]: 0: *Root(13)

In[59]: help(part1)
*** This prints the manual of outlineItem and I found the 'level' function which looks interesting for me ****

In[61]: part1.level()
Out[61]: 0

In[62]: root.level()
Out[62]: -1

In[65]: ch1 = part1.childItems[1]

In[66]: ch1.level()
Out[66]: 1

In[78]: ch1.parent().children().index(ch1)
Out[78]: 1

*** Now I know how to use/navigate the model from an index or from the root item, and I can write the function I wanted to write. I'll also probably test it in the console without restarting the app until bugs are ironed out ***

[gedakc]

I regression tested this without specifying --console and without installing the IPython, qtconsole and matplotlib libraries and Manuskript continued to work normally. As such I will rebase and merge this enhancement to help developers of Manuskript.