Make LUA scripting work even if proxmark3 is called from arbitrary working directory

- add @gpakosz whereami library (https://github.com/gpakosz/whereami) in order to ...
- determine and set absolute paths for LUA scripts and LUA libraries

client/proxmark3.h

@@ -17,5 +17,7 @@
 #define PROXPROMPT "proxmark3> "
 
 void SendCommand(UsbCommand *c);
+const char const *get_my_executable_path(void);
+const char const *get_my_executable_directory(void);
 
 #endif