Fixed comment for euclidean bundling,
which is now supports raidal bundling independently
from other intrinsics.
Use threaded cost function, jacobian and linear solver
computation, so bundling is as fast as it could be with
current parameter block structure.
Move radial distortion code to own templated function

This shall not lead to any functional changes, just
avoids radial distortion code duplicated in camera
intrinsics and bundling code.

For fancier bundle adjustment support of  different
distortion models this is not actually enough and
would need to make some bigger changes, but this
changes makes code a bit easier to maintain already.
Increase verbosity level for reprojected markers info

This information is useful, but in cases when you, say,
working on a bundler it's annoying to scroll all the
information up.
Modal (aka tripod) solver rework

Several major things are done in this commit:

- First of all, logic of modal solver was changed.
  We do not rely on only minimizer to take care of
  guessing rotation for frame, but we're using
  analytical rotation computation for point clouds
  to obtain initial rotation.

  Then this rotation is being refined using Ceres
  minimizer and now instead of minimizing average
  distance between points of point of two clouds,
  minimization of reprojection error of point
  cloud onto frame happens.

  This gives quite a bit of precision improvement.

- Second bigger improvement here is using bundle
  adjustment for a result of first step when we're
  only estimating rotation between neighbor images
  and reprojecting markers.

  This averages error across the image sequence
  avoiding error accumulation. Also, this will
  tweak bundles themselves a bit for better match.

- And last bigger improvement here is support of
  camera intrinsics refirenment.

This allowed to significantly improve solution
for real-life footage and results after such
refining are much more usable than it were before.

Thanks to Keir for the help and code review!
Fixed incorrect order of arguments passing
to EXPECT_EQ in keyframe selection tests.