Line break after pipe

[lorenzwalthert]

This PR implements the rule that %>% must usually be followed by a new line. 99% of the cases are:

blue %>% green() 
# is turned into
blue %>%
  green()

Exceptions are various constellations within function calls. This is discouraged practice anyways but we don't want to make things worse

call(a, b %>% c())

# won't be turned into
call(
  a, b %>% 
    c()
)
# or similar

See test files added in this PR for more examples.

Reason: It's not non-invasive and comes at a technically high cost (relatively large slow-down for edge case), more complex code.

call(d = g(b) %>% 
  c)

should probably be turned into

call(
  d = g(b) %>% 
    c
)

But it is not, again because of the same reasons. A more natural choice would be

call(d = g(b) %>% c)

in many cases.

This closes #470.

[codecov-io]

Codecov Report

Merging #503 into master will decrease coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #503      +/-   ##
==========================================
- Coverage   90.26%   90.25%   -0.02%     
==========================================
  Files          39       39              
  Lines        1675     1672       -3     
==========================================
- Hits         1512     1509       -3     
  Misses        163      163

Impacted Files	Coverage Δ
R/style-guides.R	100% <100%> (ø)	⬆️
R/rules-line-break.R	100% <100%> (ø)	⬆️
R/transform-files.R	100% <100%> (ø)	⬆️

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