Installing and running examples

To install:
The examples are provided within geant4_vmc package; to build all available examples:
```
cd geant4_vmc/examples
make
```
Setting environment:
First, make sure that you have included all libraries paths in your shared library path.
For all MCs:
```
/your_path/root/lib
/your_path/geant4_vmc/lib/tgt_platform
```
For G3 only:
```
path to Pythia6 library
/your_path/geant3/lib/tgt_platform
```
For G4 only:
```
/your_path/CLHEP/lib
/your_path/geant4/lib/platform-compiler
/your_path/geant4_vmc/lib/tgt_platform
optionally paths to external graphics libraries
```
- Since version 2.13, if you have installed Geant4 manually (with GNUmake) you need to replace the macro geant4_vmc/examples/macro/g4libs.C with g4libs_old.C. This will use the liblist program instead of geant4-config script for building the list of Geant4 libraries to be loaded.
- If you have installed Geant4 manually (with GNUmake) with global libraries, you need to switch the comment in g4libs.C (or g4libs_old.C) as follows:
```
void g4libs() {
   // g4libs_granular();
   g4libs_global();
}
```

To run:

cd geant4_vmc/examples/E01 or E02 or E03 or E06
root.exe 
root[0] .x run_g3.C or .x run_g4.C