digital/packet_utils: adding parameter to take a user input preamble to the packet encoder
Digital/pkt: adding ability to dynamically change preamble for pky.py
blocks: New block to convert streams to tagged streams
filter-based block tree search
Add 'Find Blocks' action and auto-hide search entry box
Removed the 'Add' button. Who used that anyway?
wxgui: ensure flowgraph shutdown before app exit

Also updates qtgui
Merge remote-tracking branch 'skoslowski/search_block_tree'
Allow variable vlen in GRC generated hier blocks
Merge branch 'maint'
Merge branch 'master' into next
Merge remote-tracking branch 'mrberman/master'
Merge branch 'master' into next
GRC: fix key event handling while the search box is active
Merge remote-tracking branch 'skoslowski/search_block_tree'
Merge branch 'master' into next
GRC: show categories from XML tree files in search
channels: Added option to block tags from propagating
digital: Fixed bug where OFDM Tx hier block would ignore 2nd sync word
digital: Rewrite of ?x_ofdm.grc examples to allow all configs with minimal user interaction, make clearer