Surround trig, exponent, log expressions with parentheses

[enjeck]

• Make it more clear that exponents are being applied to the entire log versus the contents of the log, possibly by adding a set of brackets or parentheses that encompass the entire log.
• when 1 is replaced by cos^2(x)+sin^2(x), put parentheses around it
• Trig and log functions are functions. Their arguments deserve to be protected by parens.
• The bracketing style (lim expr) is better than lim (expr)