Looking at Chris Larson's code for starting the user's editor for
"recipetool newappend" it was slightly better than what I wrote for
"devtool edit-recipe" in that it checks VISUAL as well as EDITOR and
defaults to vi if neither are set, so break this out to its own function
and call it from both places. The broken out version passes shell=True
however in case it's a more complicated command rather than just a name
of an executable.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

If you specify a URL ending in /, BitBake's fetcher returns a localpath
of ${DL_DIR}, and if you then try to unpack that it will attempt to copy
the entire DL_DIR contents to the destination - which at least on my
system filled my entire /tmp. Obviously we should fix the fetcher, but
at least detect and stop that from happening here for now.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

For scripts that use Python's standard argparse module to parse
command-line arguments, create a subclass which will show the usage
the usage information when a command-line parsing error occurs. The most
common case would be when the script is run with no arguments; at least
then the user immediately gets to see what arguments they might need to
pass instead of just an error message.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

So far all devtool and recipetool plugins were expected
to have plugin_init function. This function is empty in
most of plugins as they don't require initialisation.

Making plugin_init optional would allow not having empty
plugin_init in every plugin.

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>

This will now also be used by "devtool upgrade".

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

If -x is specified and the specified URI was a git repository, we need
to ensure that the resulting clone is a sandalone and not one that has
pointers into the temporary fetch location or DL_DIR (since the git
fetcher does a local clone with -s). Split out the code from devtool
that already does this for "devtool modify -x" and reuse that.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>

Add a utility module for scripts. This is intended to provide functions
only really useful before bitbake has been found (or only of particular
interest to scripts). At the moment this includes functions for setting
up a logger and for loading plugins.

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>