Add examples from 4.6 versions

[rjleveque]

From clawpack-4.x/apps, see http://depts.washington.edu/clawpack/users-4.6/apps.html:

• acoustics/1d/example1/ as acoustics_1d_example1
• acoustics/1d/example2/ as acoustics_1d_example2
• acoustics/2d/example1/ as acoustics_2d_radial
• advection/1d/example1/ as advection_2d_outflow
• advection/2d/annulus/ as advection_2d_annulus
• advection/2d/example1_gauges/ as advection_2d_square
• advection/2d/swirl/ as advection_2d_swirl
• burgers/1d/sine2n/ as burgers_1d_sine2n
• burgers/2d/pwconst/ as burgers_2d_square
• euler/1d/hump/ as euler_1d_hump

[gradylemoine]

Did acoustics_1d_example1 (pull request #45).