Bug fixes & DL dependencies when specified

Solves #78 (closed) and #77 (closed) and #76 (closed)

Introduces a scripts/depends.bash $BUILD_FOLDER to download all dependencies to fix version numbers and avoid segfaults because the system was updated and version numbers changed.

You can use configure --with-depends to dl and build dependencies.

depends/depends.txt

 curl    sqlite3     https://www.sqlite.org/src/tarball/sqlite.tar.gz?r=release  sqlite3.tar.gz
 wget    sdl2        https://www.libsdl.org/release/SDL2-2.0.12.tar.gz           sdl2.tar.gz
 wget    libcurl     https://curl.haxx.se/download/curl-7.72.0.tar.gz            libcurl.tar.gz
+wget    zlib        https://zlib.net/zlib-1.2.11.tar.gz                         zlib.tar.gz