Update the glacier explorer app

[fmaussion]

I prepared the data for a number of improvements to the app.

The data is available here, as hdf for faster reading. You can read the data with:

df = pd.read_hdf('rgi62_era5_itmix_df.h5', 'df')

This is a full RGI dataframe, allowing the following improvements to the app:

• Thanks to ERA5 as source we now have the Antarctic glaciers as well
• There is data from the consensus volume estimate paper: with this, there could be a vertical or horizontal bar plot somewhere, showing how much sea-level-rise the selected glaciers represent
• At the risk of making the app more complex: there is also a new climate column called "trend" with the 40-yr temperature trend from ERA for each glacier (https://fabienmaussion.info/2019/08/29/era5/). This could form a third informative histogram for "where are glaciers warming faster"
• There are several glacier categories: marine terminating, land-terminating, ice caps. There could be a drop-down selection bar to take only these

@pat-schmitt and/or @zschirmeister , would you have time to tackle these? I suggest to start from the existing app here: https://github.com/OGGM/bokeh-apps/tree/master/glaciers-explorer , move it to a new repository and update it step by step. This would be awesome!

[fmaussion]

Ups forgot the data link: https://cluster.klima.uni-bremen.de/~fmaussion/misc/rgi62_era5_itmix_df.h5

Edited above as well

[zschirmeister]

I will have a look at it. (@pat-schmitt )