* internal/flags: use filepath.Clean instead of path.Clean
* internal/flags: fix windows pipe issue
* internal/flags: modify test for windows
* internal/flags: use backticks, fix test
This change updates our urfave/cli dependency to the v2 branch of the library.
There are some Go API changes in cli v2:
- Flag values can now be accessed using the methods ctx.Bool,
ctx.Int, ctx.String, ... regardless of whether the flag is 'local' or
'global'.
- v2 has built-in support for flag categories. Our home-grown category
system is removed and the categories of flags are assigned as part of
the flag definition.
For users, there is only one observable difference with cli v2: flags must now
strictly appear before regular arguments. For example, the following command is
now invalid:
geth account import mykey.json --password file.txt
Instead, the command must be invoked as follows:
geth account import --password file.txt mykey.json
