cppcheck: fix some reports

[serval2412]

vbox.h:356] -> [vbox.h:357]: (warning) Opposite conditions in nested 'if' blocks lead to a dead code block.
[vbox.h:416]: (style) Statements following return, break, continue, goto or throw will never be executed.
[vbox.h:420]: (style) Statements following return, break, continue, goto or throw will never be executed.

[serval2412]

I also noticed this one:
[floppyIO.cpp:176]: (error) Memory is allocated but not initialized: dataToReceive
which seems a bit serious and I don't know how to fix it:
171 char * dataToReceive = new char[this->szInput];
172 int dataLength = this->szInput;
173
174 // Find the size of the input string
175 for (int i=0; iszInput; i++) {
176 if (dataToReceive[0] == '\0') {
177 dataLength=i;
178 break;
179 }
180 }
Indeed, dataToReceive can contain anything.