reducing number of 'expensive operations' in fvar
clean up matrix inverse for fvar
testing fvar functions
added fvar<var> and fvar<fvar<T> > tests for abs, acos, acosh, asin, asinh, atan2, atan
fixed spacing in fvar functions between ) and {
replaced x * x with square(x) in fvar
removed extra test files
added fvar<fvar<T>> and fvar<var> tests for atanh
added fvar<var> and fvar<fvar<T>> tests to ceil and cbrt
added fvar<var> and fvar<fvar<T>> tests to cos and cosh
added fvar<var> and fvar<fvar<T>> tests to erf and erfc
added fvar<var> and fvar<fvar<T>> tests to exp, exp2, expm1
added tests for fvar<var> and fvar<fvar<T>> to fabs, fdim, floor, fma
added fvar<var> and fvar<fvar<T>> tests to fmax, fmin, fmod
added fvar<var> and fvar<fvar<T>> tests to hypot, inv_cloglog, lbeta, inv_logit, log_inv_logit
added fvar<var> and fvar<fvar<T>> tests to log1m_inv_logit, log_inv_logit, log_sum_exp, log
added fvar<var> and fvar<fvar<T>> tests for log1m_inv_logit, log1m, log1p_exp
added fvar<var> and fvar<fvar<T>> tests for log10, log2, log1p, log1m
added fvar<var> and fvar<fvar<T>> tests to logit and operator_addition
added fvar<var> and fvar<fvar<T>> tests for operator_divide_eq, operator_div, operator_eq, operator_gte, operator_gt, operator_lte, operator_lt