Update EP7 vector data

[rogerkuou]

Fix #128

• [x] bbox tip
• [x] remove point/line/polygon image
• [x] One step cropping
• [x] Rotate lines -> optional
• [x] More vector processing:
  • [x] Buffers
  • [x] Union
  • [x] sjoin

More Todos after March 30 ITC workshop

• [x] add a general explanation on DataFrame and Series and how they are related to GeoDataFrame and GeoSeries
• [x] no need to stress clip_by_rect function, this raises quite some confusion
• [x] the sjoin function can be introduced by extending the buffer-cropping exercise. The result of this exercise is clipped. We can use sjoin to extract the polygons in the original shape

[rogerkuou]

Hi @fnattino and @rbavery, I updated the EP7, with more on vector data processing. When you have time, could you give a view on this? Thanks!

[rogerkuou]

Hi @fnattino, thx for the review! I made some updates based on your feedbacks. Would you like to give a one last look?

[rogerkuou]

Since there are feedbacks we get from a workshop on March 30, I am converting this one back to draft and implement them

[rbavery]

Hi @rogerkuou ! apologies for the late comment on this, I'll give this a review this week.