hghave: move feature checking into hghave.py Upcoming patches will kill hghave (the script - not hghave.py) and will move to a model where requirements checking is performed as a function call. Start diminishing the utility of hghave by moving some code to hghave.py.

tests: move '#require bzr' into .t files The bzr tests are the only .t tests calling hghave (aside from the tests testing hghave itself). This pattern is a one-off and prevents desired refactors to how requirements checking is integrated into tests. Use the convention used everywhere else.

commands.push: use "pushloc" path attribute Path instances now have a "pushloc" attribute that exposes the path to be used for pushing. The "default-push" path is automatically captured in the "pushloc" attribute of the "default" path. Drop references to "default-push" and use the "pushloc" attribute for looking up where to push to.

ui: capture push location on path instances Currently, we treat "default" and "default-push" as separate paths, even though they are the same logical entity but with different paths for different operations. Because they are the same entity and because we will eventually be implementing an official mechanism for declaring push URLs for paths, we establish a "pushloc" attribute on path instances. We populate this attribute on the "default" path with the "default-push" value, if present. This will enable consumers stop referencing "default-push" which will make their code simpler.