Remove dynamic exception specification (closes #689)

[eddelbuettel]

Two commits in here:

• the first is narrow and just removes the dynamic exception mechanism as discussed in Deprecation warnings on g++ 7.1.0 at MacOS 10.12.4 #689
• the second looks invasive but just removes a bunch of spaces.

[codecov-io]

Codecov Report

Merging #690 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #690   +/-   ##
=======================================
  Coverage   89.77%   89.77%           
=======================================
  Files          66       66           
  Lines        3511     3511           
=======================================
  Hits         3152     3152           
  Misses        359      359

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ebe67e8...3727360. Read the comment docs.

[eddelbuettel]

Anyone? Shall I just squash it in?