Add -wait and -ssl <lib> options

[rgov]

Features:

• Added a -wait flag that spins until the named process launches. This is useful if the target process's lifecycle is not directly controlled by the user.

• Added a -ssl <lib> flag that allows the user to resolve ambiguities where multiple libSSL libraries are present in the target process. Without this change, the Frida script gives up if multiple libraries match *libssl*.

Misc:

• Added a requirements.txt file to make it easier to install Frida. Granted, there is only the one dependency, but the Frida.re website leads the user to install Frida command line tools, not the main package itself.

• Simplified argument parsing code. Optional arguments (-xyzzy) are not required by default, and the store_true action simplifies some boolean flags (and appropriately sets the default).