Adjust size of figure according to the plots inside to improve performance

closes #195 (closed)

closes #158 (closed)

Testing showing that the big starting figure size can slow down performance. This MR will scale down the size of figure by:

• Using width of screen to be the starting width of figure
• Using 25 as maximum height of SOH and waveform. This number is selected to make sure all channels are plotted and the height of main_widget is covered to avoid artifact.
• For TPS, the figure will be created after the figure's height is calculated. This way we don't have to be afraid to set a too big starting height which slow down the processing performance or a too small starting height with cut off plotting data for a long time range (many years) Size of TPS will be adjust based on request to improve performance, and avoid the case TPS is cut off when plotting data for long time range (many years).

Decide to remove ratio_w from label's font size so the font size keep the same for any resolution.

The new method improve the performance for the data set with short time like RT130-sample

	old	new
SOH	6.9s	2.6s
WF	5.2s	1.3s
TPS	3.2s	0.77s

For the dataset which lasts for many years like 6407.sdr, it has less impact

	old	new
SOH	39.53s	18.56s
WF	37.26s	16.03s
TPS	44.69s	41.55s
	47.73s	45.32s
	50.86s	48.93s