Build external libraries by cmake.

[gongminmin]

For better building experiences, replace those external's project files with cmake's:
1. Python
2. libogg
3. libvorbis
4. 7z
5. freetype

[gongminmin]

Convert 7z in changeset 6d3321d48aa9e0c7d77f0fa38a26f723b8589482; libogg in 3c8e2c4a91ff66ae54059a1c0bf6c90a46bf9a7e; libvorbis in facee9be1ccd8953cff8ef71472238aae9daae17; freetype in 6f060cdf720eb5ec76dab4490c2e20de4a782c86.

[gongminmin]

Deferred python with cmake to the future.

[gongminmin]

Updated in changeset 2731b8446330ba55f250f0a508a1e49c59aaa960, utilize the cmake for python from  https://github.com/gongminmin/python-cmake-buildsystem.

[gongminmin]

Done in changeset 7ed8597ccdaf458dab2f441a861ee185aa662500.