A small frontend to the libcURL library.

Configuration
-------------

!<config>
! <libc stdout="/dev/log" stderr="/dev/log">
!  <vfs>
!   <dir name="dev"> <jitterentropy name="random"/> <log/> </dir>
!  </vfs>
! </libc>
! <fetch url="http://genode.org/about/LICENSE" path="LICENSE" retry="3"/>
! <report progress="yes"/>
!</config>

The two primary options are 'url', the URL to fetch, and 'path', the
file-system path where fetched data is written. Secondary options are
'retry' and 'proxy'. Retry is the number of fetch attempts to make
following failure, and proxy is used to reroute requests.

An example TOR proxying configuration:

! <fetch url="http://genode.org/about/LICENSE" path="LICENSE"
!        proxy="sock5://10.0.0.1:9050" />

The presence of a 'report' node in the configuration with an
affirmative 'progress' attribute will enable a progress report.
The 'delay_ms' attribute will set the minimum interval between
reports and defauts to 100 miliseconds. The report format is as
follows.

! <progress>
!   <fetch url="..." total="100.0" now="50.0"/>
! </progress>
