filemerge: print the filename in quotes in prompt
This is better as the filename is in quotes and user can understand better what
the filename is and what is important part in the prompt.
Differential Revision: https://phab.mercurial-scm.org/D4373
filelog: remove proxies to revlog
These proxy attributes and methods were added to facilitate various
debug* and perf* commands. Now that cmdutil.openrevlog() returns
an actual revlog, we no longer need these on the filelog class.
There's probably a few other attributes that could be removed. But
this feels like a worthy start.
Differential Revision: https://phab.mercurial-scm.org/D4359