CSV Reading uses too much memory due to full file reads

[ShreyasKhandekar]

In the CSVMsg module, read_csv uses too much memory which causes Segmentation fault when the program runs out of memory.

This is arising due to the following pattern which appeared in many places in the module:

var lines = reader.lines().strip();

This reads the entire file into memory, and when the file sizes are huge relative to the memory available, the server crashes.
#3238 improved the situation here by eliminating this pattern from read_files_into_dist_array, but lsCSVMsg and get_info still use this pattern and cause crashes.