tuned naming

added lemma asymp_on_asym_on_eq[pred_set_conv]

strengthened and renamed asymp_less and asymp_greater

added lemmas asym_on_subset and asymp_on_subset

added lemmas asym_onI, asymp_onI, asym_onD, and asymp_onD

added predicates asym_on and asymp_on and redefined asym and asymp to be abbreviations

clarified state and process; support to load document session_background (which can take 1-2s in AFP);

clarified signature;

clarified signature;

clarified signature;

clarified signature;

merged

strengthened and renamed symp_symclp

merged

Tuned text

clarified signature: avoid confusion due to redundant standard_path, which is already used here (but not elsewhere);

clarified signature: avoid case class with redefined equality;

discontinued somewhat pointless dependency: avoid illusion of extra accuracy (see also 09fb749d1a1e and 0f750a6dc754);

tuned;

clarified signature;

unused;

clarified signature;

tuned whitespace;

tuned;