Do not crash in find() if array is empty

This fixes FS 1292, but with my own slightly different patch.
simplify return statement
Cleanup: don't hand-implement binary search -- use std::lower_bound instead
Do not include <complex>, it is not used
Fixes compilation error due to missing header.
[BlockVector]
modify constructor with capacity to catch at least some of the
wrong invocations (see doxygen comment).
Fixes overwritten right hand side for FastAMG with one level.

Unfortunately, SuperLU always overwrites the right hand side with
the solution. Therefore we now copy it if there is only one level
in the matrix hierarchy of AMG.
add header to Makefile.am to make nightly build happy
wrong header files added in commit e193b96ca295e4fd5b7d56a2acc04d9599525a9d
removed again - sorry about that.
[CMake] Fixes typo in header list and thus installation