vfs: define "join()" in each classes derived from "abstractvfs" This patch defines "join()" in each classes derived from "abstractvfs" except "vfs", which already defines it. This allows all vfs instances to be used for indirect file API invocation.

store: initialize vfs field first to use it for initialization of others This patch initializes "vfs" field in the constructor of each store classes to use it for initialization of others. In this patch, "self.vfs.base" is used to initialize "self.path", because redo join of path components for "self.path" is redundant.

scmutil: reorder newly added functions for vfs support in dictionary order Definition functions for vfs support in dictionary order increases readability/maintainability, because there are functions which invoke file API: - with same name: "os.listdir" and "osutil.listdir", for example - with ambiguous names: "os.mkdir" and "util.makedirs", for example

store: rename field name from "opener" to "vfs" in internal classes for fncache These fields are used only in store module, so keeping "self.opener" for backward compatibility like as "localrepository" class is not needed.

store: rename argument name from "op"(ener) to "vfs"

verify: rename "hasmanifest" variable for source code readability Before this patch, there are two ambiguous variables: "havemf" and "hasmanifest". "havemf" means whether there are any "manifest" entries. "hasmanifest" means whether there are any "changelog" entries referring to "manifest" entry. This patch renames from "hasmanifest" to "refersmf" to clear difference from "havemf".

verify: use appropriate local variable in "checkentry()" Before this patch, "checkentry()" internal function uses both "node"(argument of itself) and "n"(defined in outer of it) variables. Because all callers of "checkentry()" use "n" to refer the object which is passed to "checkentry()" as "node", both can refer same object in "checkentry()". So, "checkentry()" works correctly. But such usage is not good for independence of "checkentry()". This patch replaces "n" in "checkentry()" with "node".