Remove Mapsource .mps format (#588)

Remove Mapsource .mps format (#588)

* Fix numerous instances of shadowing confusion.

Inspired by a cppcon talk and our recent conversations about warnings, I
took a closer look at shadowing variables in our code and I wasn't proud
of my findings.

We had a lot of code that was writing to local variables or function
arguments when it thought it was operating on globals or (soon)
method-member variables. I made a rather half-hearted pass at changing
this by splitting up huge functions, renaming arguments, renaming globals
to reflect their future status as method variables (foo_), and generally
cleaning things up. The amound of effort I spent on each format was
approximately equal to its expected lifespan - I'm not spending an hour
on cleanups on formats I should instead be deleting.

In a future submit, I'll try to find some combination of -W flags on
our targets that allows us to not regress easily.

* Fix merge conflict I just created in gdb.cc

* Delete workspace.xml

* Delete the same link in garmin_icons.xml that I deleted twice yesterday.
Fix more esoteric warnings.

* Reapply MORE of yesterday's commits.
Seriously, I know this has been committed and is in HEAD...

* Attempt to fix list detachment within route.cc

* Remove Mapsource

The Mapsource format has been deprecated by Garmin for something
like 15 years. Later versions of Mapsource used GDB and Basecamp,
Garmin's first replacement for the Mapsource lineage, was used
exclusively in later versions.

I've reviewed list traffic and floated a discussion on the list.
The code style was never really very flexible and it it bears
a high maintenance cost that we can no longer afford. This
format is dead.

* Remove more pieces of Mapsource.

* Change Netstumbler test to not use Mapsource for staging.
More cleanups.

* Fix netstumbler so I can delete Mapsource. Ugh.

* Update netstumbler with IWYU.