Move package versions from index.html back into the src/*.mk files

Most of the automatic conversion was done using the following Python script:

import os
import re
pkgs = sorted(mkfile[:-len('.mk')] for mkfile in os.listdir('src') if mkfile.endswith('.mk'))
with open('index.html', 'rb') as f:
    index = f.read()
pkgs_index = re.findall('<td class="package">([^<]*)</td>', index)
assert pkgs_index == pkgs
versions = dict(re.findall('<td id="([^"]*)-version">([^<]*)</td>', index))
assert sorted(versions.keys()) == pkgs
for pkg in pkgs:
    version = versions[pkg]
    with open('src/' + pkg + '.mk', 'rb') as f:
        mk = f.read()
    checksumpos = mk.index('\n$(PKG)_CHECKSUM ')
    versionline = '\n$(PKG)_VERSION  := %(version)s' % {'version': version}
    newmk = mk[:checksumpos] + versionline + mk[checksumpos:]
    with open('src/' + pkg + '.mk', 'wb') as f:
        f.write(newmk)