TypeScript: NoImplicitReturns support

[MeFisto94]

When "noImplicitReturns": true, in the tsconfig.json, then at least the misc.ts yields a compiler error:

    cv.toMatTypeName = (type: number): MatTypes | undefined => {
        for (const t of allTypes) {
            if (cv[t] === type) return t;
        }
    };

Here, in case the type couldn't be found, we'd need to explicitly return undefined

[UrielCh]

Patched as:

cv.toMatTypeName = (type: number): MatTypes | undefined => {
    for (const t of allTypes) {
        if (cv[t] === type) return t;
    }
    return undefined;
};