Fixes#669Closes#368Closes#624
Deprecate PRINTT, PRINTV, PRINTI, and PRINTF
Default STRFMT("%f") to 5 fractional digits like "{f:}"
Any use of string formatting will share this default
Document the existing `ROUND`, `CEIL`, and `FLOOR` functions
Also update the trig function docs for searchability
Implement `POW` and `LOG`
Addresses part of #675
Implement ** for integer exponents
** has higher precedence than -, like Python, so -3**4 == -(3**4) == 81