Improved our argument parsing abilities to be able to handle stuff more like

a shell would interpret it. A few examples that we now handle correctly

INPUT: "Hello "world
OUTPUT: "Hello World"

INPUT: "Hello "' World'
OUTPUT: "Hello World"

INPUT: Hello" World"
OUTPUT: "Hello World"

This broke the setting of dictionary values for the "settings set" command
for things like:

(lldb) settings set target.process.env-vars ["MY_ENV_VAR"]=YES

since we would drop the quotes. I fixed the user settings controller to use
a regular expression so it can accept any of the following inputs for
dictionary setting:

settings set target.process.env-vars ["MY_ENV_VAR"]=YES
settings set target.process.env-vars [MY_ENV_VAR]=YES
settings set target.process.env-vars MY_ENV_VAR=YES

We might want to eventually drop the first two syntaxes, but I won't make
that decision right now.

This allows more natural setting of the envirorment variables:

settings set target.process.env-vars MY_ENV_VAR=YES ABC=DEF CWD=/tmp

llvm-svn: 122166