Rather than stopping the program immediately, we allow the
density-matrix normalization step to try to recover the correct number
of electrons. This is non-optimal but can recover from occassional
instabilities.

Update the manual.

Create Docs/LitCode to hold the .html files produced (manually for now) from
the .lit files in Src.

added:
  Docs/LitCode/
  Docs/LitCode/README
  Docs/LitCode/pexsi-dos.html
  Docs/LitCode/pexsi-ldos.html
  Docs/LitCode/pexsi-lit.html
  Docs/LitCode/pexsi-solver.html
  Docs/LitCode/redist-spmatrix.html
renamed:
  Src/redist-spmatrix.org => Src/redist-spmatrix.lit
modified:
  Docs/siesta.tex
  Src/Makefile
  Src/m_pexsi_driver.F90
  Src/makefile.lit
  Src/pexsi-solver.lit
  Src/redist-spmatrix.lit