Updated installation instructions.

Based on suggestions from Sven Kaßbohm.
Add test to check induced drag for elliptic planform.
Tweaks to installation instructions.
Add cmake version requirement.
Allow synthesis of panel neighborhood relationships across surfaces.
Use PCA to flatten panels.
Explicitly specify preconditioner.
Use symbolic view names.

Thanks to Sven Kaßbohm for the suggestion.
Remove debug code.
Output surface velocity distribution as well.
Implement streamline tracing.
Simplify stitching.
Store target neighbor edge information in Surface::panel_neighbors.
Solver::trace_streamline:  Do not try to intersect any edge that we may be on.
Test for convergence as well in test-elliptic-platform.
SurfaceBuilder::create_panels_between_shapes():  Use triangles when appropriate.
Add example of NACA airfoil section with rounded tips.
Add example of NACA airfoil section with rounded tips.
Merge branch 'master' of baayen-heinz.com:/home/BaayenHeinz/gitweb/Vortexje

Conflicts:
	examples/naca0025-rounded-tips.cpp
Correct file name for NACA0025 rounded tips example.