.editorconfig

revset: introduce an API that avoids `formatspec` input serialization

Instead of having the data fully serialized, the input can be directly inserted
in the tree at a later stage.

Just using it for simple "%ld" case provide a significant boost. For example
here are the impact on a sample discovery run between two pypy repositories
with arbitrary differences (using hg perfdiscovery).

$ hg perfdiscovery
before: ! wall 0.700435 comb 0.710000 user 0.700000 sys 0.010000 (median of 15)
after:  ! wall 0.501305 comb 0.510000 user 0.490000 sys 0.020000 (median of 20)

# See http://EditorConfig.org for the specification

root = true

[*.py]
indent_size = 4
indent_style = space
trim_trailing_whitespace = true

[*.{c,h}]
indent_size = 8
indent_style = tab
trim_trailing_whitespace = true

[*.t]
indent_size = 2
indent_style = space
trim_trailing_whitespace = false