Fix Linux 64bit GCC compilation, adjust Makefile

[CounterPillow]

There are still lots of warnings, mostly related to dangerous casts, but it compiles and is able to show the help output with GCC 5.2.0.

Makefile

• COMPILER_OPTIONS was replaced with the standard convention of CXXFLAGS for C++ files.
• LINKER_OPTIONS was replaced with the standard convention of LDFLAGS.
• g++ was replaced with $(CXX), which by default is g++ for GNU Make.
• all was made a phony target due to not creating an output named "all".
• A phony target clean was added, which calls $(RM) (equivalent to rm -f in GNU Make by default) on the output files.
• Replaced -march=core2 with -march=native. Closes issue #13.

Code

• Fix a number of compilation errors by turning calls to members in some places to dependant(?) calls by prefixing this->.
• Turn is_power_of_2 into a template to solve ambiguity errors related to calling it with size_t.
• Explicitly cast a size_t to uint32 in one place to resolve an ambiguity error. Might be incorrect, but I'm not knowledgeable enough with C++ to propose a cleaner fix.
• Systems other than Windows can have 64 bits too.

All in all, most likely closes issue #10.

[MAnyKey]

It is a good pull request. Why isn't it merged?

[CounterPillow]

I assume because the project is dead.

[richgel999]

We're busy with several projects that have paying customers.