v0.5.0

• Added method to create blank spreadsheets #253
• Added method to clear worksheets #156
• Added method to delete a row in a worksheet #337
• Changed Worksheet.range method to accept integers as coordinates #142
• Added default_blank parameter to Worksheet.get_all_records #423
• Use xml.etree.cElementTree when available to reduce memory usage #348
• Fixed losing input_value data from following cells in Worksheet.insert_row #338
• Deprecated Worksheet.get_int_addr and Worksheet.get_addr_int in favour of utils.a1_to_rowcol and utils.rowcol_to_a1 respectively