cc: @valsson

Notice that this change required a bit of hacking.
setAveragingAction now takes a std::unique_ptr as an argument.

I think ownership is clearer now since it is explicitly declared.

immediately assign newly created object to unique_ptr

(see 5c8e4631)

LDSHARED was erroneously reset in configure.

cc: @hanatok

Notice newer cppcheck versions are slower. In order to make the check fit
on travis-ci I had to make a few extra changes:
- better optimization flags when building cppcheck
- force a number of ifdefs in the check

Now master takes approx 25 minutes, so we have room for adding new code.

I removed the remaining delete statements.

Notice that in order to make this change I had to change a bit the interface
of a few functions. The difficulty here is that there are parts of the
code storing a reference to a std::vector of pointers and those are affected
when the vector is transformed into a vector of unique_ptr.

Fixed typo (see #369)