mercurial: add editorconfig Editorconfig (http://editorconfig.org/) is a file format helping define coding styles like spaces, tabs etc. It supports a wide range of editors. Some well- known projects like ruby and zsh are using it already. This patch adds a simple .editorconfig, making it clear we use 8-char tabs in C code, 4-char spaces in Python code, and we don't keep trailing spaces.

parsers: fix istat macro to work with single line if statement

pypy: fix setdiscovery test This test relies on the exact details of random.sample given the seed. Things work a bit differently under pypy, make the test less specific.

chg: wrap line at 80 chars This is a style fix. I was using tabstop=4 for some early patches, although I realized we use tabstop=8 later but these early style issues remains. Let's fix them.

chg: replace abortmsg showing errno with abortmsgerrno Since we have abortmsgerrno now, use it to show human friendly error messages across platforms.

chg: add util function abortmsgerrno to print error with errno It's common to abortmsg with the errno information. Let's make a utility function for it.

chg: use color in debug/error messages conditionally Before this patch, chg always uses color in its debugmsg and abortmsg and there is no way to turn it off. This patch adds a global flag to control whether chg should use color or not and only enables it when stderr is a tty and HGPLAIN is not set.

revset: force ascending order for baseset initialized from a set It is possible to initialize a baseset directly from a set object. However, in this case the iteration order was inherited from the set. Set have undefined iteration order (especially cpython and pypy will have different one) so we should not rely on it anywhere. Therefor we declare the baseset "ascending" to enforce a consistent iteration order. The sorting is done lazily by the baseset class and should have no performance impact when it does not matter. This makes test-revset.t pass with pypy.