add boilerplate functions for better print() output of styles

[numericOverflow]

These simple functions allow for easier debug so the style classes play nice with print()

print() now outputs:

 EdgeStyle(label='MY_LABEL', color='None', caption='label', directed='True', curve_style='None')

instead of:

<st_link_analysis.component.styles.EdgeStyle object at 0x7f6bb9ac9fd0>