changed __main__ pipeline to process cluster class

With addition of cluster class for handling and manipulating
gene expression data, the functions and pipelines that handle
these data has now been changed to accept and process the data
from cluster instances.

With all class-associated modifications complete, this also makes
this commit version 2.0
fixed pathname bugs and data-import error

the export pathway was being assigned to the same path as the data
table directory, causing results to not be saved. Added variable
for cluster class to select cwd as default, and allow importing
of a user-defined pathway to set for all export functions.

Also updated the module functions to use the new attribute
for exporting data.
fixed colour normalisation in table

cluster class was adjusting the vmax and vmin in the wrong (opposite)
conditions to when it was supposed to. This was fixed, and some of
the output messages have also been amended for improved clarity
in what the program is actually processing (and a better printout
of restults.