Shortfall and sacrifice: that's how the Texas Legislature two years ago defended gutting $5.4 billion from public education, laying off thousands of public workers with slashed spending and stripping Medicaid to the bone.  The Texas economy is humming. Unemployment is at a four-year low of 6.2 percent, sales tax receipts are skyrocketing and money is pouring in to state coffers behind a new energy boom, fueled by oil gushing in West Texas and a fracking frenzy from North Texas to San Antonio.  Currently, Medicaid is the biggest issue though. Lawmakers must pay a $4.7 billion tab on the state's health program for its poorest residents and the disabled before writing a new budget for 2014-15.   Gov. Rick Perry and other top GOP leaders want to limit spending increases to a formula of population growth plus inflation. Nonetheless, Lawmakers will have much to discuss next week with the start of the 83rd legislative session.