A couple of modules were relying on the fact that the 'sys' module was being implicitly imported by 'from py23 import *'.
The 'py23.__all__' does not include 'sys'. I think it's better to always import 'sys' explicitly when needed.
Since py23 modifies some essential builtins, it's safe to import
everything all the time. At least, that's how it was designed.
It's a bug if importing * breaks some code.
The previous 'allXMaxIsLsb' name was misleading.
The 'allXMinIsLsb' boolean variable cooresponds to the head table's Bit 1.
This is set whenever all glyphs have the bbox.xMin equal to the respective
left sidebearing (and therefore "left sidebearing point at x=0").
Today, Apple has kindly fixed a bug in the [specification of the
meta table](https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6meta.html). The existing fonttools implementation matches the
revised specification. Therefore, the comments about fonttools
intentionally deviating from Apple's spec can be removed.
'featurefile' can be either a path (string) or a file object, like in TTFont or XMLReader and XMLWriter constructors.
If a file object does not have a 'name' attribute, a default "<features>" name is
used and the current working directory is assumed as the root for relative includes.
The code that is being removed is untested and does not seem to make
fixing an overflow any easier. The fixer code just needs to know
which subtable caused the overflow and does not care about the item
within. As such, no point in trying to find a "right" item.
In fact, leaving item as is, is more useful in debugging overflows
as it reflects which item's offset actually overflowed.
Part of fixing https://github.com/behdad/fonttools/issues/537
According to the spec:
> The lookupflag attribute defaults to 0 at the start of a feature
> block.
>
> The lookupflag attribute stays the same until explicitly changed, until
> a lookup reference statement is encountered that changes it, until the
> script is changed, or until the end of the feature.
This is an attempt to fix this by resetting the lookupflag at the start
and end of feature/lookup blacks. I’m not sure if resetting it in lookup
blocks is correct (my reading of the spec suggests it is not), but one
needs to test this against makeotf and see how it behaves here.
