deprecate maptools for sunset / sunrise calculation

[adokter]

With deprecation of maptools package (#545) sunrise and sunset calculation is lost in its current form.

Functions currently parsing an argument to sunrise / sunset functions (usually elev, the solar elevation defining sunset / sunset):

• as.data.frame.vp()
• as.data.frame.vpts()
• check_night()
• check_night.default
• check_night.vp
• check_night.list
• check_night.vpts
• check_night.vpi
• check_night.pvol
• filter_vpts()
• plot.vpi()
• sunrise()
• sunset()

[adokter]

Option 1: Package suncalc provides sunrise/sunset times

• pros: no sp dependence, maintained by others
• cons: no sun elevation argument, would require elev argument deprecation in all above functions

Option 2: A skeleton package with former maptools sunrise/sunset functions is available, which could be copied into bioRad

• pros: no need to change anything
• cons: sunMapTools still dependent on sp, which will be deprecated in the future

Option 3: strip out sp methods from sunMaptools, use only what we need

• pros: keeps elev argument, less refactor in bioRad
• cons: another piece of code to maintain ourselves

[adokter]

see also #500

[baptischmi]

Option 1: Package suncalc provides sunrise/sunset times

• pros: no sp dependence, maintained by others
• cons: no sun elevation argument, would require elev argument deprecation in all above functions

Option 2: A skeleton package with former maptools sunrise/sunset functions is available, which could be copied into bioRad

• pros: no need to change anything
• cons: sunMapTools still dependent on sp, which will be deprecated in the future

Option 3: strip out sp methods from sunMaptools, use only what we need

• pros: keeps elev argument, less refactor in bioRad
• cons: another piece of code to maintain ourselves

Note that for suncalc::getSunlightTimes(), the 'elev' argument is categorised in the keep argument. Available variables are :
"sunrise" : sunrise (top edge of the sun appears on the horizon)
"sunriseEnd" : sunrise ends (bottom edge of the sun touches the horizon)
"goldenHourEnd" : morning golden hour (soft light, best time for photography) ends
"solarNoon" : solar noon (sun is in the highest position)
"goldenHour" : evening golden hour starts
"sunsetStart" : sunset starts (bottom edge of the sun touches the horizon)
"sunset" : sunset (sun disappears below the horizon, evening civil twilight starts)
"dusk" : dusk (evening nautical twilight starts)
"nauticalDusk" : nautical dusk (evening astronomical twilight starts)
"night" : night starts (dark enough for astronomical observations)
"nadir" : nadir (darkest moment of the night, sun is in the lowest position)
"nightEnd" : night ends (morning astronomical twilight starts)
"nauticalDawn" : nautical dawn (morning nautical twilight starts)
"dawn" : dawn (morning nautical twilight ends, morning civil twilight starts)

[bart1]

Hi not very relevant any more but for future reference I would not go for the suncalc package as long at this issue is not resolved: datastorm-open/suncalc#8