Create general plot methods

[Tom-Kingstone]

Description:

From LadybugTools_Toolkit, move methods for all base plot types (that don't require any more than numpy, matplotlib, pandas and other common libraries) to this toolkit, and in ladybugtools remove the old base plots and instead reference the new ones here.

Plot methods to be moved:

• diurnal
• heatmap
• histogram
• spatial_heatmap
• timeseries

This will also cover moving bhom_analytics to Python_Toolkit instead and calling it from everywhere else.