Use revlogng and inlined data files by default
This changes revlog specify revlogng by default. Inlined
data files are also used unless a flags option is found in the .hgrc.
Some example hgrc files:
[revlog]
# use the original revlog format
format=0
[revlog]
# use revlogng. Because no flags are included, inlined data files
# also be selected
format=1
[revlog]
# use revlogng but do not inline the data files with the index
flags=
[revlog]
# the new default
format=1
flags=inline