dbparser 1.1.2

Enhance many memory and performance issues for many parsers.
Change the drug classigication represenations to extract more useful infromation. ### Minor Changes
Change some drug tibbles features names ### DEFUNCT
Size columns in drugs main table is no longer exist, will do full statistical analysis later using dvminer package.

dbparser 1.1.1

Functions have been splitted into 6 categories DrugBank Database Loading, Carriers, Targets, Transporters, Drug and common parsers. All function names are changed to reflect the function family. The related documentation is also updated (#66, #75).
dbparser now can cite the package by calling citation("dbparser") (#71).
Adding more user friendly error messages (#76, #81).
User can now pass DBI database connection to parser functions as an argument beside SQLite and MariaDB (#87).

open_db, open_mdb and close_db functions are no longer supported. Creating and maintaining database is completely user responsibility and the database connection can be passed to parser functions (#87).

New tutorials for how to use dbparser have been created (#78, #79).
Contribution guide has been added.
Code of conduct has been added (#70).
Enhance function reference documentation to include section for each type (#68).

Fix zip file location issue
Replace Secondary and third keys columns from drug framework with other_keys column that contains any other keys that might exist in addition to the primary key
Add average-mass, monoisotopic-mass and calculated-properties parsers.
Support saving parsed drugs related parsed database as csv