#25 indexing etc. patch
0005-Matlab-style-colon:
colon creates an array like in Matlab: '1:4' ->{1,2,3,4}, '0:2:6' -> {0,2,4,6}
0006-improve-LIBGC-support:
When Boehm GC(LIBGC) is used, temporal vectors can be thrown away、improving time consumption in vec_gc() loop.
0007-fix-parse-nesting-indexing:
Fix bug in 0004-parse-recursive-indexing-foo-bar-n posted in another thread: Both of 'foo[bar[n]]' and 'foo[[n,m]]' can work well.
0008-Matlab-style-indexing:
If "x=vector(4); reshape x[2][2]", one may expect 1x2 array {0,2} by x[0,1][0]. But current ngspice returns just 0, because it parses (x[0,1])[0] and x[0,1] be x itself, then x[0,1][0] becomes identical to x[0]. This patch can fix it. Moreover, Matlab-like indexing x[0:1][0] becomes also work. One can easily create sub-matrix by this matlab-like indexing.
to fix memory-leak in 0005 and 0008