Graphs improvements

- Show begin and end time in the graph info table
- Show "Custom" zoom resolution when zoom is active and make it clickable to jump to it later
- Hide past time comparison series by default if too high

scripts/lua/modules/http_lint.lua

@@ -1231,6 +1231,7 @@ local known_parameters = {
    ["ts_schema"]               =  validateSingleWord,
    ["ts_query"]                =  validateListOfTypeInline(validateSingleWord),
    ["ts_compare"]              =  validateZoom,
+   ["initial_point"]           =  validateBool,
 
    -- json POST DATA
    ["payload"]                 =  validateJSON,