build: Upgrade to SDK-18 (JellyBean 4.3).
eclipse: Remove project metafiles *SEE COMMIT MESSAGE*.

These files don't belong in the git repository since they are user-
specific and subject to change based on eclipse version.  After merging
this commit, you will need to regenerate your own version of these
files.  Here's how:

 1. In eclipse "Delete" the project from your workspace (but don't
    delete the actual files)
 2. Close eclipse and manually delete the above three files (if they
    aren't already)
 3. Open eclipse and File->Import... "Existing Android Code Into
    Workspace"
 4. Right-click project->Android Tools->Fix Project Properties
 5. Right-click project->Android Tools->Add Native Support...
      a. Enter name "Dummy" and click Finish
      b. Manually delete jni/Dummy.cpp
 6. If you want multi-core compilation (dramatically faster builds),
    go to Project->Properties->C/C++ Build
      a. Uncheck "Use default build command"
      b. Set build command to
           ii.  "ndk-build -j3" if your build machine runs 2 cores
           i.   "ndk-build -j6" for 4 cores
           iii. "ndk-build -j12" for 8 cores
           iv.  etc.
 7. For auto-formatting the Java code (ctrl-shift-f), be sure to
    import the formatting settings located in ./doc/config_files/

When this is all done, the C/C++ indexer should work properly and
resolve #includes correctly.  The drawback (besides the initial
recreation) is that you'll have to redo this process every time you
jump to an old revision where the files are tracked, then jump back to
the newer revision.  The easy solution to this is to just back up your
untracked files and restore them every time git deletes them after the
reset.