fix for Logarithmic Scale Tick Bug for values of 0

[roicos]

Fix for iss#3917 and iss#2966.
The minNotZero value is based on fontSize now (like recomended here) (i closed the previous pr because of too many conflicts).

[etimberg]

does subtracting diff work when the axis is horizontal and the labels are rotated less than 90 degrees?

[roicos]

Horizontal chart looks like this (values: 0.01, 4, 0, 63, 10, 0.5)

[jcopperfield]

The proposed fix for doesn't work for charts without 0, as can be seen in the attached chart.

Problems
v2.7

• doesn't correctly render: horizontal with min:0 (regular and reversed)
• in case the significand digit of minNotZero is 1 or 2;
  however the value itself has more significand digits,
  the first tick is displayed outside the chart area or on top of the 0-tick.

The pull request

• doesn't correctly display charts without zero values
• adds space for all log-lines up to 1, which the generators.logarithmic doesn't create.

Proposed fix
fix_for_logarithmic_scale_tick_bug_for_values_of_0.patch
.patch files aren't allowed in upload, so it's renamed as .txt

Example
Test for all bar plot possibilities (vertical/horizontal, with/without min: 0, default/reversed)
https://codepen.io/anon/pen/zPYMWz

[benmccann]

A fix for this was implemented in #4913