Merge branch 'hotfix/1-searchable'
Merge branch 'release/v0.2.0'
Merge branch 'release/v0.2.5'
Merge branch 'release/v0.2.6'
Added test for empty values on properties in ACD/Labs tab
chemspider source now handles vague search requests
Added test for empty values on properties in ChemSpider ExtendedCompoundInfo API
created stub for NIST parser
Starting with fixing the wikiparser
added several required imports
Wikipediaparser now works on chemboxes as well
new_compound_request now returns a Request with a searh URL
NIST now scrapes the symbol table for later use
search NIST exclusively for phase change data
added code to recognize various table formats
created function to start scraping the aggregate data table
added function to scrape transition tables
added function for most generic tables
added function to scrape table for Antoine equation parameters
fixed scraping of unit for two kinds of tables