fixes include statement for east cascades merchantability

was previously, {{include.EC_merch.txt}} --> changed to
{{include.EC_merch}}
updates override default site index comment for CA variant
splits pine beetle calculation into two separate include files

necessary because the NC variant does not have lodgepole pine species
code, so cannot calculate lodgepole pine beetle risk.  also updates
keyfiles to have two separate include statements for beetle risk
calculation, one for ponderosa pine and one for lodgepole pine.