.editorconfig

errors: introduce InputError and use it from commands and cmdutil

This patch introduces a `InputError` class and replaces many uses of
`error.Abort` by it in `commands` and `cmdutil`. This is a part of
https://www.mercurial-scm.org/wiki/ErrorCategoriesPlan. There will
later be a different class for state errors (to raise e.g. when
there's an unfinished operation). It's not always clear when one
should report an input error and when it should be a state error. We
can always adjust later if I got something wrong in this patch (but
feel free to point out any you notice now).

Differential Revision: https://phab.mercurial-scm.org/D9167

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

root = true

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

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

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