blocks: Added callback to vector source GRC bindings
digital: clock recovery fix relative limit
digital: clock recovery delete unused variables
digital: clock recovery more verbose documentation
digital: adapt clock recovery QA
digital: applying same fix of the complex M&M clock recovery block as the float vrsion.
blocks: convert asserts to throwing runtime errors in keep_m_in_n ctor.
blocks: fixed up keem_m_in_n to handle relative rate and correct number of items in calls to work.

Original patch from Zhe Feng on mailing list.
build_guide: Make explicit we only support Qt4
grc: yet another py26 incompatibility
grc: fix search entry box for old PyGTK versions
grc: update all flowgraphs when hiding port labels
grc: no icon in search entry box for old PyGTK versions
grc: fix lagging drag and drop
grc: fix missing xterm (Bug #725)
grc: fix lagging drag and drop, round two