Add script to install build depend for Debian

Add a script debian/deb-build-dep. The script parses debian/control file
and installs the necessary build time dependent packages to the system:

   $ sudo ./debian/deb-build-dep
Debian package: fontforge conflict fontforge-nox

remove sugguestion to install both.
import Tsukurimashou's enhanced fontlint
Merge pull request #1035 from mskala/new-fontlint

import Tsukurimashou's enhanced fontlint
Fixed crashes due to failing to set had_layer_cnt after call to SFD_GetFontMetaData().
geteol instead of getname for FontName value.
Merge pull request #1040 from fontforge/fix_932

geteol instead of getname for FontName value.
Log meaningful warning instead of silently dropping invalid substitutions

When trying to Generate TTF from a font where some rlig substitutions
refer to nonexistent glyphnames, the lookup subtable is silently marked
as unused and then dropped. Traced this in GDB and fixed it.
warning: suggest parentheses around '&&' within '||'
Merge pull request #1041 from JoesCat/master

[PATCH] Log a meaningful warning instead of silently dropping invalid substitutions
Don't crash if NameCompare or TtfNameCompare are passed null pointers.
Fixed crash in PyFFContour_GetSplineAfterPoint().

When contour.getSplineAfterPoint(0) is called and contour.is_quadratic
is false, it causes the array self->points[] to be accessed with an
negative index, resulting in a crash or invalid data being used.  The
original code attempted to handle this condition but did so
incorrectly.  Now fixed.
Fixed incorrect conditional test in PyFFContour_GetSplineAfterPoint()

When contour.getSplineAfterPoint() is called and
contour.is_quadratic() is false, the point corresponding to the given
point number is examined and if point.on_curve is true, the point
number is decremented, and if point.on_curve is still true,
decremented again.  The author presumably intended to handle
the situation in which the given point was actually a control point,
in which case both of those tests need to be reversed, testing
point.on_curve for false.  Fixed.
Integers being incorrectly passed to Py_BuildValue() expecting double.

Py_BuildValue() takes a variable-length list of arguments whose types
are determined by a format string.  This means that the compiler
cannot perform the usual type checking and size conversions that it
would normally do.  In this case, an integer zero was being passed as
an argument for which the format specifier was "d", meaning that a C
double was expected.  On machines where int and double are not the
same width, this guarantees corruption of arguments on the stack.

The fix is to substitute 0.0 for 0 in these arguments, which C treats
as constant of type double.
Merge pull request #1044 from blipvert/fixes/17

Fixed crashes and data corruption in PyFFContour_GetSplineAfterPoint()
Merge pull request #1043 from blipvert/fixes/16

Don't crash if NameCompare or TtfNameCompare are passed null pointers.
Merge pull request #1039 from blipvert/fixes/15

Fixed failure to set had_layer_cnt in SFD_GetFont()
buffer overrun errors
resource leak
Merge pull request #1047 from JoesCat/master

leaks, buffer overrun