Merge pull request cs50#188 from cs50/develop

Removes stdlib.h and byte, adds stddef, adds static library

Removes stdlib, adds stddef, removes byte (cs50#185)

Merge pull request cs50#183 from cs50/develop

adds back get_long_long for Windows

Merge pull request cs50#179 from cs50/develop

9.0.2

Merge pull request cs50#164 from cs50/develop

A few clarifications, fixes

Merge pull request cs50#152 from cs50/develop

2019 version

Merge pull request cs50#139 from cs50/soname

fixed soname

Merge pull request cs50#135 from cs50/style

updated style of cs50.c for consistency

Merge pull request cs50#129 from cs50/repo

cs50/repo

Merge pull request cs50#95 from cs50/develop

fixing -Wmissing-field-initializers