Update RDoc and make minor changes in the jdbc hsqldb subadapter
Update RDoc and make minor changes in the jdbc hsqldb subadapter

Database#server_version was renamed to db_version and is now an
integer. HSQLDB now respects Dataset#for_update to lock rows.
I've added some minor CTE related methods to HSQLDB, but CTE
support is still disabled as it has signficant issues.

reubano/sequel,beni55/sequel,Marketcircle/sequel,gferguson-gd/sequel,nju520/sequel,yazshel/sequel,dennis-d/custom_sequel,offshore-safety/sequel,pfarrell/sequel,nju520/sequel,t-morgan/sequel,pfarrell/sequel,knut2/sequel,yazshel/sequel,freshpay/sequel,knut2/sequel,chef/sequel,seeARMS/sequel,seeARMS/sequel,dennis-d/custom_sequel,nicohvi/sequel,reubano/sequel,t-morgan/sequel,uhoh-itsmaciek/sequel,gferguson-gd/sequel,davidbegin/sequel,beni55/sequel,bigfix/sequel,offshore-safety/sequel,davidbegin/sequel,mpalmer/sequel,uhoh-itsmaciek/sequel,nicohvi/sequel,freshpay/sequel,offshore-safety/sequel,mpalmer/sequel