Can I change a setting or option so that when I move the cursor to the left margin, it allows me to just click to select the entire line of text instead of dragging down to the next line?
With the keyboard: "Shift+End". 
I think a triple click does what you want.
triple click marks the whole paragraph 
Hmm – I need four clicks for the whole paragraph.
Double click to select a word, triple click to select a sentence.
@horst and @manj_k - your discussion let me make a test at LibO 3.6.5.2 on XPProf/SP3
I observe the same as manj_k mentioned
Double click to select a word. Triple click to select a sentence. Quad click to select a paragraph. Shift plus end in order to select from the point of clicking to the end of the line.