firfilt: moving to common non-recursive filter prototype
firfilt: adding method to convert getopt string to filter type
build: makefile cleanup (trivial)
asgram: fixing scaling when computing dB
fft/spgram: scaling gain by sqrt(2) so output level matches
buffer/wdelay: cleaning up code, adding descriptive comments
build: add DESTDIR support in makefile for RPMs, custom installation
fft/spgram: moving object declaration to macro
fft/spgram: moving internal object definition to macro
fft/spgram: adding spgramf object (real inputs) and example
build: removing unnecessary vpath make directive

  * liquid has a simple build environment with well-defined paths
  * no need to perform any silly searches for dependencies
  * explicitly listing internal header dependencies in makefile.in
ofdmframesync: cleaning up synchronization example a bit
ofdmframesync: simplifying frame sync example

  * notching spectrum
  * loading different modulation symbols on different subcarriers
  * simplifying channel model