Replaced vendored openpyxl by a dependency

Thanks Tommy Anthony for the initial patch.

setup.py

@@ -49,23 +49,19 @@
     'tablib.packages.xlwt',
     'tablib.packages.xlrd',
     'tablib.packages.odf',
-    'tablib.packages.openpyxl',
-    'tablib.packages.openpyxl.shared',
-    'tablib.packages.openpyxl.reader',
-    'tablib.packages.openpyxl.writer',
     'tablib.packages.yaml',
     'tablib.packages.dbfpy',
     'tablib.packages.xlwt3',
     'tablib.packages.xlrd3',
     'tablib.packages.odf3',
-    'tablib.packages.openpyxl3',
-    'tablib.packages.openpyxl3.shared',
-    'tablib.packages.openpyxl3.reader',
-    'tablib.packages.openpyxl3.writer',
     'tablib.packages.yaml3',
     'tablib.packages.dbfpy3'
 ]
 
+install = [
+     'openpyxl',
+]
+
 
 setup(
     name='tablib',
@@ -90,5 +86,6 @@
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
     ),
+    install_requires = install,
     tests_require=['pytest'],
 )

tablib/compat.py

@@ -26,7 +26,6 @@
     import tablib.packages.xlrd3 as xlrd
     from tablib.packages.xlrd3.biffh import XLRDError
     from tablib.packages import markup3 as markup
-    from tablib.packages import openpyxl3 as openpyxl
     from tablib.packages.odf3 import opendocument, style, text, table
     import tablib.packages.dbfpy3 as dbfpy
 
@@ -48,7 +47,6 @@
     from tablib.packages.xlrd.biffh import XLRDError
     from tablib.packages import markup
     from itertools import ifilter
-    from tablib.packages import openpyxl
     from tablib.packages.odf import opendocument, style, text, table
 
     from tablib.packages import unicodecsv as csv

tablib/formats/_xlsx.py

@@ -11,7 +11,7 @@
 else:
     from cStringIO import StringIO as BytesIO
 
-from tablib.compat import openpyxl
+import openpyxl
 import tablib
 
 Workbook = openpyxl.workbook.Workbook
@@ -51,7 +51,8 @@ def export_book(databook, freeze_panes=True):
     """Returns XLSX representation of DataBook."""
 
     wb = Workbook()
-    wb.worksheets = []
+    for sheet in wb.worksheets:
+        wb.remove_sheet(sheet)
     for i, dset in enumerate(databook._datasets):
         ws = wb.create_sheet()
         ws.title = dset.title if dset.title else 'Sheet%s' % (i)
@@ -111,42 +112,38 @@ def dset_sheet(dataset, ws, freeze_panes=True):
         _offset = i
         _package.insert((sep[0] + _offset), (sep[1],))
 
+    bold = openpyxl.styles.Font(bold=True)
+    wrap_text = openpyxl.styles.Alignment(wrap_text=True)
+
     for i, row in enumerate(_package):
         row_number = i + 1
         for j, col in enumerate(row):
             col_idx = get_column_letter(j + 1)
+            cell = ws.cell('%s%s' % (col_idx, row_number))
 
             # bold headers
             if (row_number == 1) and dataset.headers:
-                # ws.cell('%s%s'%(col_idx, row_number)).value = unicode(
-                    # '%s' % col, errors='ignore')
-                ws.cell('%s%s'%(col_idx, row_number)).value = unicode(col)
-                style = ws.get_style('%s%s' % (col_idx, row_number))
-                style.font.bold = True
+                # cell.value = unicode('%s' % col, errors='ignore')
+                cell.value = unicode(col)
+                cell.font = bold
                 if freeze_panes:
-                    # As already done in #53, but after Merge lost:
                     #  Export Freeze only after first Line
                     ws.freeze_panes = 'A2'
 
             # bold separators
             elif len(row) < dataset.width:
-                ws.cell('%s%s'%(col_idx, row_number)).value = unicode(
-                    '%s' % col, errors='ignore')
-                style = ws.get_style('%s%s' % (col_idx, row_number))
-                style.font.bold = True
+                cell.value = unicode('%s' % col, errors='ignore')
+                cell.font = bold
 
             # wrap the rest
             else:
                 try:
                     if '\n' in col:
-                        ws.cell('%s%s'%(col_idx, row_number)).value = unicode(
-                            '%s' % col, errors='ignore')
-                        style = ws.get_style('%s%s' % (col_idx, row_number))
-                        style.alignment.wrap_text
+                        cell.value = unicode('%s' % col, errors='ignore')
+                        cell.alignment = wrap_text
                     else:
-                        ws.cell('%s%s'%(col_idx, row_number)).value = unicode(
-                            '%s' % col, errors='ignore')
+                        cell.value = unicode('%s' % col, errors='ignore')
                 except TypeError:
-                    ws.cell('%s%s'%(col_idx, row_number)).value = unicode(col)
+                    cell.value = unicode(col)