Fix "No tests found"

[potterzot]

When running 'devtools::check()', reports no tools found. Also should fix the other warnings that are included in this output:

checking Rd \usage sections ... WARNING
Undocumented arguments in documentation object 'biome_to_input'
  ‘biomes’
Documented arguments not in \usage in documentation object 'biome_to_input':
  ‘biome’

Undocumented arguments in documentation object 'calc_ghgv'
  ‘eco’
Documented arguments not in \usage in documentation object 'calc_ghgv':
  ‘eco_json’
... 16 lines ...

Undocumented arguments in documentation object 'str2LogicalOrNumeric'
  ‘string’
Documented arguments not in \usage in documentation object 'str2LogicalOrNumeric':
  ‘x’

Functions with \usage entries need to have the appropriate \alias
entries, and all their arguments documented.
The \usage entries must correspond to syntactically valid R code.
See chapter ‘Writing R documentation files’ in the ‘Writing R
Extensions’ manual.

checking for hidden files and directories ... NOTE
Found the following hidden files and directories:
  .dockerignore
These were most likely included in error. See section ‘Package
structure’ in the ‘Writing R Extensions’ manual.

checking DESCRIPTION meta-information ... NOTE
License components with restrictions not permitted:
  FreeBSD + file LICENSE
Package listed in more than one of Depends, Imports, Suggests, Enhances:
  ‘rmarkdown’
A package should be listed in only one of these fields.

checking top-level files ... NOTE
Non-standard files/directories found at top level:
  ‘Dockerfile’ ‘README.Rmd’ ‘README.html’ ‘Rserv.conf’ ‘start.R’

checking R code for possible problems ... NOTE
plot_ghgv: warning in brewer_pal(pal = "Greens"): partial argument
  match of 'pal' to 'palette'
plot_ghgv: warning in brewer_pal(pal = "Blues"): partial argument match
  of 'pal' to 'palette'
calc_ghgv: no visible binding for global variable ‘output_formats’
get_biome: no visible global function definition for ‘read.csv’
get_biome: no visible binding for global variable ‘Value’
get_biome: no visible global function definition for ‘na.omit’
get_biome: no visible binding for global variable ‘Zone’
... 11 lines ...
write_plot: no visible global function definition for ‘png’
write_plot: no visible global function definition for ‘dev.off’
write_plot: no visible global function definition for ‘svg’
Undefined global functions or variables:
  Biome CODE Location Order Value Zone dev.off na.omit output_formats
  png read.csv reorder svg value variable write.csv
Consider adding
  importFrom("grDevices", "dev.off", "png", "svg")
  importFrom("stats", "na.omit", "reorder")
  importFrom("utils", "read.csv", "write.csv")
to your NAMESPACE file.