record section xtick error enhancement

[aakash10gupta]

There are different issues which show up when using the record section plotting tool for different sets of data -

• no xticks are seen as such for the case coded in the python script no_xtick.txt.
  

• xticks are so large in number that it takes a lot of time for the figure to show up, and the x-axis gets saturated for the case coded in the python script saturated_xtick.txt. Even though some of this can be handled by setting xtick_minor and xtick_major, it will greatly help to have an automated way to adjust this, if possible.
  

• it would also be helpful to have an option to have absolute 'datetime' as xticks for record sections, especially for the ones with longer time lengths.

[bch0w]

• No major xticks on short record sections bugfix: too many xticks #89
• Too many xticks on long record sections bugfix: too many xticks #89
• Convert xticks to datetime (not relative time)