After 2b2aca1, DictCompiler/Decompiler's `arg_delta` method unconditionally attempts to get the first item to check if it's a list, but this fails with `IndexError` when the value is empty.
```
Traceback (most recent call last):
[...]
File "/Users/cosimolupo/Documents/Github/ufo2ft/Lib/ufo2ft/otfPostProcessor.py", line 15, in __init__
otf.save(stream)
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/ttLib/__init__.py", line 219, in save
self._writeTable(tag, writer, done)
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/ttLib/__init__.py", line 658, in _writeTable
tabledata = self.getTableData(tag)
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/ttLib/__init__.py", line 669, in getTableData
return self.tables[tag].compile(self)
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/ttLib/tables/C_F_F_.py", line 20, in compile
self.cff.compile(f, otFont)
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/cffLib.py", line 124, in compile
writer.toFile(file)
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/cffLib.py", line 300, in toFile
endPos = pos + item.getDataLength()
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/cffLib.py", line 1858, in getDataLength
return len(self.compile("getDataLength"))
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/cffLib.py", line 1879, in compile
data.append(arghandler(value))
File "/Users/cosimolupo/Documents/Github/fonttools/Lib/fontTools/cffLib.py", line 1910, in arg_delta
val0 = value[0]
IndexError: list index out of range
``
Before this change, some table statements would allow empty statements
(just a semicolon) while others would not allow them. After this change,
we're more consistent.
Set Coverage.Format to 1. This is rather arbitrary, which is exactly
why Coverage.Format doesn't make sense and should not have been
exposed to begin with.
and viceversa, convert '\n' back to '\r' when reading from XML.
This restores the original newline handling of asciiTable, but only for VOLT's private tables.
This is just to make the tests pass, otherwise the following re.sub call fails with TypeError on Python 3.
However, I wonder why we need to replace all newlines with spaces in 'Notice' and 'Copyright' fields?
```
if name in ['Notice', 'Copyright']:
value = re.sub(r"[\r\n]\s+", " ", value)
```
We shall ask Read about this.
