First attempt - don't merge :)

Hi Yosef, 

This is completely unnecessary pull request but it's a first attempt of mine (don't forget that I know C even less than Python :)). 

Question 1 - is this is the workflow we're talking about? I took one function from the C-TclTk project, called epi.c, stripped it off, left only two functions, took from globals.h and typedef.h the necessary headers into epi.h, put the header into /include, put the epi.c into src of the liboptv and added test_epi.c to the /tests folder, I also fixed the CMakeLists.txt

I haven't tested it yet, I'll do it next step, after you reject the pull request but say that I understood correctly your instructions. 

I need a lot of C code help, especially all kind of pointer type, address type, etc. I'm a bit lost. In addition, I don't know how to write tests, so I'll need also some easy instructions from you. 

Thanks,
Alex
P
PS. Please be gentle.