Added lightweight title option - #237

@teddyrowan
Teddy,
Thank you so much for contributing to mplfinance. This is a great idea. If you agree, I think it would be nice to make this more generic: As you may have noticed with some of the other kwargs in mplfinance, the kwarg accepts either a specific value, or a dict which can contain any additional modifiers for the function being called by mplfinance (in this case fig.suptitle).

The simplest way for me to explain what I have in mind is to write some of the code here. If you like the idea, then please integrate it (or similar) into your local clone and then push to your fork (which will then automatically propagate to this PR).

if config['title'] is not None:
    if config['tight_layout']:
        # IMPORTANT: 0.89 is based on the top of the top panel
        #            being at 0.18+0.7 = 0.88.  See _panels.py
        # If the value changes there, then it needs to change here.
        title_kwargs = dict(size='x-large',weight='semibold', va='bottom', y=0.89)
    else:
        title_kwargs = dict(size='x-large',weight='semibold', va='center')
    if isinstance(config['title'],dict):
        title_dict = config['title']
        if 'title' not in title_dict:
            raise ValueError('Must have "title" entry in title dict')
        else:
            title = title_dict['title']
            del title_dict['title']
        title_kwargs.update(title_dict)  # allows override default values set by mplfinance above
    else:
        title = config['title']      # config['title'] is a string
    fig.suptitle(title,**title_kwargs)

With the above code, instead of:

mpf.plot(data,...,title='MyTitle',title_lightweight=True,...)

you would do:

mpf.plot(data,...,title=dict(title='MyTitle',weight='light')....)

You can now accomplish the same thing you want and have the flexibility to choose any weight ([ 'normal' | 'bold' | 'heavy' | 'light' | 'ultrabold' | 'ultralight']) as well as to modify any other kwargs available to fig.suptitle() ([x, y,ha,va,fontsize,weight]).

Let me know what you think. If you agree to integrate the above code (please check it; I have not tested it) then you will have to also modify the validator for kwarg "title" to allow dict in addtion to str; and you can then also remove kwarg "title_lightweight".

Thanks. All the best. --Daniel

P.S. Please also move the version (src/mplfinance/_version.py) up one notch. That is why the PR check is failing. We have a check in place to make sure that every PR increases the version number a notch. Thanks.

@DanielGoldfarb

You're right, that was a much more elegant and useful way to implement the change. All parameters for suptitle are now able to be modified and there should be no issues for old code that inputs title as a string. Your code worked great.

Teddy, Thank you so much for contributing to mplfinance. Wishing you all the best. --Daniel