Removed output_itemized_energy(), added compute pair support

<I>ecoul</I>.  The output of these quantities is controlled by the

<A HREF = "thermo.html">thermo</A> command.

</P>

<P>This pair style also tallies a breakdown of the total ReaxFF potential

energy into sub-categories, which can be accessed via the

<A HREF = "compute_pair.html">pair compute style</A> command. The 14 entries

in the vector generated by the compute pair command correspond

to the following sub-categories (the variable names in italics match those

used in the ReaxFF FORTRAN library): 

</P>

<OL><LI><I>eb</I> = bond energy

<LI><I>ea</I> = atom energy

<LI><I>elp</I> = lone-pair energy

<LI><I>emol</I> = molecule energy (always 0.0)

<LI><I>ev</I> = valence angle energy

<LI><I>epen</I> = double-bond valence angle penalty

<LI><I>ecoa</I> = valence angle conjugation energy

<LI><I>ehb</I> = hydrogen bond energy

<LI><I>et</I> = torsion energy

<LI><I>eco</I> = conjugation energy 

<LI><I>ew</I> = van der Waals energy

<LI><I>ep</I> = Coulomb energy

<LI><I>efi</I> = electric field energy (always 0.0)

<LI><I>eqeq</I> = charge equilibration energy 

</OL>

<P>In order to print these quantities to the log file (with descriptive

column headings) the following LAMMPS commands can be 

included in the input script:

</P>

<PRE>compute reax all pair reax

variable eb  	 equal c_reax[1]

variable ea  	 equal c_reax[2] 

 \:

variable eqeq 	 equal c_reax[14]

thermo_style custom step temp epair v_eb v_ea ... v_eqeq 

</PRE>

<P>Only a single pair_coeff command is used with the <I>reax</I> style which

specifies a ReaxFF potential file with parameters for all needed

elements.  These are mapped to LAMMPS atom types by specifying N