Add Scorecard plotting function

Hi @aho,

I open this issue in order to add a function to plot Scorecards. Last week we had a meeting with @nperez and @nmilders where we agreed to include this function in the new 'esviz' package. There's still some work to do in the script but since the CSSCorecards is private, I've included the code in branch: develop-scorecard. The changes will be made in !7 (merged).

New scripts:

• Function SCPlotScorecard -> New VizScorecard ?
• Auxiliary function: .SCLegend
• Auxiliary function: .SCTableColors

Dependencies:

• Module Phantomjs
• Package kableExtra
• From s2dv: Reorder
• From ClimProjDiags: Subset

Here below I have some comments:

1. Do you think having the Phantomjs dependency could be a problem in the future? Also, this module would need to be installed in hub. I thin k it has not been installed yet, I can open an issue in requests if it's needed.
2. Maybe I will move the auxiliary functions needed in the same file as SCPlotScorecard. Only if the functions can't be used in other contexts.

Cheers,

Eva