Address various suggestions for improvement from cppcheck output

[brash99]

I started looking into using cppcheck to analyze source code. I started with the hcana/src directory, but of course this should be applied to the entire Hall A analyzer as well, in principle.

Cppcheck produced a lot of suggestions for improvement, which break down into several categories:

a) warnings about unused variables, etc.
b) potential performance hits
c) style issues

I took some time to fix a few of the things that showed up from categories a) and b) ... that was pretty simple. However, there remain to broad types of things that cppcheck complains about:

1. C-style pointer casting
2. Failure to initialize member variables in the constructor of a class.

Below is the output of cppcheck from just one of the pieces of source code in hcana/src:

[src/THcAerogel.cxx:263]: (style) C-style pointer casting
[src/THcAerogel.cxx:267]: (style) C-style pointer casting
[src/THcAerogel.cxx:273]: (style) C-style pointer casting
[src/THcAerogel.cxx:279]: (style) C-style pointer casting
[src/THcAerogel.cxx:285]: (style) C-style pointer casting
[src/THcAerogel.cxx:305]: (style) C-style pointer casting
[src/THcAerogel.cxx:454]: (style) C-style pointer casting
[src/THcAerogel.cxx:52]: (warning) Member variable 'THcAerogel::fPosGain' is not initialized in the constructor.
[src/THcAerogel.cxx:52]: (warning) Member variable 'THcAerogel::fNegGain' is not initialized in the constructor.
[src/THcAerogel.cxx:52]: (warning) Member variable 'THcAerogel::fA_Pos' is not initialized in the constructor.
[src/THcAerogel.cxx:52]: (warning) Member variable 'THcAerogel::fA_Neg' is not initialized in the constructor.
... and so on.

Looking at the first few entries, the code looks like this:

.
.
while(ihit < fNhits) {
THcAerogelHit* hit = (THcAerogelHit *) fRawHitList->At(ihit);
.
.

So, you can see the type of thing that it is complaining about. The question is: what do we do about this? One option, as I understand it, is to replace these casts with one of the C++-style casts (static_cast<...>, const_cast<...>, etc.). A second (better?) option is to use STL vectors. A third option is to just ignore this and proceed ahead.

I have to admit I don't understand at this point if the uninitialized member variable warnings are so-called "false positives" of cppcheck, or if there is some non-standard procedure that is being followed in our code.