Ease installation

[maurolepore]

Ideas (some very bad ones):

• Install packages one by one. This helps users experience multiple little successes and they can install only what they need.

  • fgeo to not install but only attach available fgeo packages?

• Make fgeo install only fgeo.base, fgeo.tool, fgeo.data, and let users install the other packages that depend on less reliable code?

• Reduce dependencies in general and particularly try to avoid less-tested packages.

• Give video-instructions to setup an updated R-environment

• Create a package to diagnose problems in users' R-environment (talk to Jenny Bryan and Jim Hester in case they are developing something along those lines -- given that they run the WTF workshop).

• Distribute built versions of all fgeo packages (source and or binary?).

• Make packages smaller:

  • Move vignettes to a bookdown?
  • Reduce/remove data?
  • Why is fgeo.habitat so heavy?

• Submit packages to CRAN so users don't need install_github().

[maurolepore]

(Relates to #63)

@teixeirak, @seanmcm,

Now fgeo is much easier to install (see Installation at https://forestgeo.github.io/fgeo/). Please test it (#64) and let me know if you have any issue.

• At first glance, the installation instructions are short.
• For more details, users can expand specific instructions
• Users with an authenticated GitHub account can install directly from GitHub -- as usual.
• Users without an authenticated GitHub account can avoid reaching the rate-limit (Avoid reaching rate limit #69) by using fgeo.install.
• For an example, users can expand and view a demo of fgeo.install.

Also, fgeo is now much lighter (#68). No information is lost.

Finally, the krigging function is now excluded from the core fgeo packages. It lives in its own package, fgeo.krig, because it depends on a problematic package (geoR). This insulates the problem.