blocks: allow the user to specify the tag key used in the tags_strobe block
modtool: dashes no longer allowed in modnames at all (fixes #619)
Merge branch 'modtool-dashes' into modtool-git
modtool: no more exit() in modtool package

Conflicts:
	gr-utils/python/modtool/modtool_newmod.py
modtool: Added git support
blocks: throttle block now looks for rx_rate tag and updates the throttle rate accordingly.  A new block parameter can tell the block to ignore these tags; set to True by default.
Merge branch 'maint'
Merge remote-tracking branch 'martin/modtool-git'
Update revision to 3.7.2.1
Merge branch 'maint'

Used merge strategy -s ours to skip release commit.
Fix a typo that prevents the Max block from working in GNU Radio Companion
when its IO Type is set to Short.
volk: removing duplicate entry for volk_8i_convert_16i.
volk: using union for float to int conversion in volk_32f_invsqrt_32f.

Removes warning about type-punned pointer. Also, produces noticeable speed increase using GCC, though slightly slower with clang.
math: fixes fast_atan2 float==0 check.

runtime: adds math functions to swig to make available as gr.function.
runtime: Moved QA code that uses blocks to the gr-blocks component.
Merge branch 'maint'