Add checks/tests for common chart errors and display them

[nsonnad]

add some prelim code for common mistake errors

add check to whether axis ticks are uneven

put chart mistakes catching in own module and add tests for it

improve tick-detection algorithm and add tests for it

add checks for large numbers, no pref/suf

set max bytes for chartProps to 240k

render axis errors inline

refine checks so that uneven/nan series can be distinguished

[yanofsky]

looks good, i'll let you deal with the merge conflicts