improve log scale buffers

[davelandry]

GDP per capita axis should not go up to 1M USD (you probably want to go up to 10 or 20% of the highest value. Which should be cutting the y-axis at about 120k
Same for the bottom limit of the y-axis. It should be 80 or 90% of the minimum value.

new d3plus.Plot()
    .data("https://dev.oec.world/api/gdp/eci?Year=2018&x=OEC.ECI&y=NY.GDP.PCAP.KD")
    .y("NY.GDP.PCAP.KD")
    .groupBy("Country ID")
    .yConfig({scale: "log"})
    .x("Trade Value ECI")
    .size("Trade Value")
    .render();