JSON extension: v2.6

[Skyhigh173]

misc change

• used single quotes
• renamed a block
• optimized get all keys, values, entries
• {"key":123} are considered valid json now (leading & trailing spaces)

blocks added

• minify json
• filter list based on text
• flip key-value pair
• import all variables (works for clones & local & global vars)
• export all variables (works for clones & local & global vars)