dispatch: allow testedwith to be bytes or str

ui: fix ui.traceback on Python 3

ui: fix opts labeling on ui.warn et al for Python 3 This is a step towards fixing extension load warnings on Python 3. Note that I suspect there are still some bugs in this area and that things like color won't work, but the code at least executes and prints text to the console correctly now.

config: add sanity assert that files are opened as binary This helps with some debugging in Python 3, and shouldn't hurt anything in Python 2. The unusual construction using getattr is done so that StringIO/BytesIO instances can be used as well as real files.

update: for "noconflict" updates, print "conflicting changes" on conflict With experimental.updatecheck=noconflict, if the update is aborted because of conlicts, "uncommitted changes" is not quite accurate. Let's use "conflicting changes" instead. Also fix the hint to recomment --clean, not --merge, since that's what we do for other failed updates.

tests: fix test-update-branches to remove non-conflicting file I was clearly very sloppy when I wrote the test case for experimental.updatecheck=noconflict. The test case that checks that one can move between commits with a removed file was deleting a file that was modified between the source and target commits, which resulted in a "change/delete" conflict. Since that is a conlict, the update correctly failed. Let's fix the test by removing a file that is not modified between the two commits.

branches: populate all template keywords in formatter This is a usage example of fm.context().

formatter: add support for changeset templating Some formatter-based commands provide fields that are identical to the ones defined in templatekw, but we had to specify them manually to support all changeset-based template keywords. This patch adds fm.context() that populates all templatekw. These keywords are available only in template output, so we still need to set important keywords via fm.data() if they should be available in e.g. JSON output. Currently fm.context() takes only 'ctx' argument. It will eventually be extended to take 'fctx' to support file-based keywords (e.g. {path}) seen in hgweb.

templatekw: move defaulttmpl constant from changeset_templater These templates are used when rendering inner lists of some template keywords, so it makes sense to define them in templatekw. This allows us to reuse them to create a templateformatter knowing changectx.

formatter: drop filters argument from maketemplater() It's unused now. I want to keep the high-level API simple.

templater: port formatnode filter from changeset_templater This slightly reduces the difference between changeset_templater and formatter, and helps extending formatter to support changeset templating. New formatnode() is not a template filter, but a function since a filter cannot access to ui. And it's marked as DEPRECATED since I think it exists only for compatibility reasons.

update: allow setting default update check to "noconflict" The new value allows update (linear or not) as long as they don't result in file merges. I'm hoping that this value can some day become the default.

update: add experimental config for default way of handling dirty wdir This allows the user to set e.g. experimental.updatecheck=abort to abort update if the working directory is dirty, but still be able to override the behavior with e.g. --merge when needed. I considered adding a --mergelinear option to get back the old behavior even when experimental.updatecheck=abort is set, but I couldn't see why anyone would prefer that over --merge. The default is read in hg.updatetotally(), which means it also applies to "hg pull -u" and "hg unbundle -u".

update: accept --merge to allow merging across topo branches (issue5125)